You have resistance to piercing and bludgeoning, but vulnerability to fire damage.

Your Wisdom score increases by 2, and your Dexterity score increases by 1.

Gelatinous live potentially forever. As long as they aren't killed or dry up, that is.

You have proficiency in the Survival Stealth.

When you are below half of your maximum HP, you count as one size smaller, with your armour shrinking with you. In this state, your dexterity modifier increases by 1 and your strength modifier decreases by 1. This does not affect your carrying capacity. (these can go above +5, and below -5)

Whenever you gain more than 5 temporary HP, you grow by one size, your strength modifier increases by 1, your armour once again growing with you.  This increases your carrying capacity respectively. You might want to write down your potential carry capacity, D&D beyond cant automate this.

You may also choose to simply become a puddle. In this form, you cannot attack, cast, move, talk, or anything that require movement. All you can do is return to a humanoid form, but you will have advantage on stealth checks, and anyone who walks over you must make a DC10 dexterity saving throw or be knocked prone. The cost of becoming this puddle is 1HP, and it takes the action: hide to do it, or 3 seconds whilst out of combat.

You can speak, read, and write Common.