Base Class: Rogue
You are an undead that stalks in darkness and feeds on the blood of the living: a vampire. Perhaps you chose this existence, or perhaps it was forced on you. Either way, you must now survive as a hated monster.
Creature of the Night
When you choose this archetype at 3rd level, your body changes along with your vampiric transformation. You are an undead instead of your normal creature type. In addition, you gain the following benefits.
Darkvision. You can see normally in dim light and darkness out to a range of 60 feet. If another source grants you darkvision, this range increases to 120 feet.
Fangs and Claws. Your mouth has fangs, allowing it to be used as a weapon that deals 1d8 piercing damage on a hit. Your hands have claws, and each hand can be used as a weapon when it is empty, dealing 1d8 slashing damage on a hit. Each weapon has the finesse property. When you hit with an attack using your fangs and use your Sneak Attack feature, the extra damage is necrotic.
Spider Climb. You have a climbing speed equal to your walking speed, and you can climb vertical surfaces and upside down on ceilings without needing to make an ability check.
However, you permanently suffer the following flaws.
Forbiddance. You can't enter a residence without an invitation from one of the occupants.
Harmed by Running Water. You take acid damage equal to 5 + your level whenever you end your turn in running water.
No Reflection. You do not appear in reflections.
Stake to the Heart. If a piercing weapon made of wood is driven into your heart while you are incapacitated, you are paralyzed until the stake is removed.
Sunlight Hypersensitivity. You take radiant damage equal to 5 + your level whenever you start your turn in sunlight. While in sunlight, you have disadvantage on attack rolls and ability checks.
Darkvision (120 feet)
You can see normally in dim light and darkness out to a range of 120 feet.
Darkvision (60 feet)
You can see normally in dim light and darkness out to a range of 60 feet.
Vampiric Healing
Starting at 3rd level, your vampiric nature lets you heal yourself, both from your innate regeneration and from the life you drain through drinking blood.
When you hit a target with an attack using your fangs and you use your Sneak Attack feature, if the target has blood, you can choose to regain a number of hit points equal to your rogue level + your proficiency bonus. This can't restore more hit points than the amount of damage dealt by your Sneak Attack feature for that attack.
Once you regain hit points in this way, you can't do so again until you finish a long rest. The number of times you can do so per long rest increases by one when you reach 11th level and 17th level in this class.
In addition, you can use a bonus action to spend up to a number of hit dice equal to half your proficiency bonus and regain hit points, as if you had finished a short rest. Whenever you take radiant damage, you can't spend hit dice in this way until the end of your next turn.
Dark Command
At 9th level, you begin to awaken your vampiric talents. You gain resistance to necrotic damage.
Also, you can cast charm person without requiring components. You can also cast the new conjure critters spell using only verbal components and without needing concentration, but the beasts appear after 1d4 rounds, they aren't considered fey, and you can only conjure bats, rats, swarms of bats, and swarms of rats. The level of each spell is equal to half your proficiency bonus, and your spellcasting ability for them is Charisma. You can end the effects of either spell as a bonus action.
You can only use this feature to cast a spell twice. You regain both expended uses when you finish a long rest.
Uncanny Transformation
At 13th level, you discover how to change your body into classic vampiric forms. When you aren't in sunlight or running water, you can use your action to take the shape of a bat or a cloud of mist, or transform back into your true form. While in bat form, you can't speak or make attacks, your walking speed is 5 feet, you are Tiny, and you have a flying speed of 30 feet. Your other statistics remain unchanged.
While in mist form, the effects are the same as those of the gaseous form spell, except that you don't gain any resistance to damage or advantage on saving throws.
When you transform, anything you are wearing transforms with you, but nothing you are carrying does. You revert to your true form if you die.
When you use your Uncanny Dodge feature, you can also transform using this feature as part of the reaction. Once you transform as part of a reaction, you can't do so again until you finish a short or long rest.
Cunning Predator
At 17th level, you achieve mastery over your vampiric traits. You can use your Dark Command and Uncanny Transformation features as bonus actions. When you do so, you can also spend hit dice using your Vampiric Healing feature as part of the same bonus action.
In addition, you regain all your missing hit dice when you finish a long rest, instead of only half, and when you spend hit dice to regain hit points, you can roll each hit die twice and use the higher result.

We are not making subclasses to change the power-level of the game. These subclasses are designed to match the power-level of existing subclasses. If you find rogue to be weak, that is due to how you play the game. Rogues are the only class that have no base resources to run out of, with loads of skill utilities and other features along with consistent damage. When DMs run the game as it is intended, rogues tend to excel, not fall behind.
I think this subclass could use another pass, there are many exceptions and overall the rules do not read well.
Try to find places to better integrate with the core Rogue class. Rogue is one of the weakest classes in the game second to monk, so it's OK to add power.
Cunning Predator should likely be much stronger or come sooner, however at the least, it should allow use of Vampiric Healing when using the rogue's cunning action feature. Wording could be simplified if Dark Command and Uncanny Transformation were appended to the Cunning Action feature.