Ways to Increase a Dhampir's Bite Damage

I'm trying to make a Dhampir tank and I need methods to increase the piercing damage, thus increasing the HP restored. I'm playing a Barbarian, so spells won't mix with this (I know, Hunter's Mark is the easiest method). Any help is appreciated!

There are a few items that increase unarmed damage, which are mainly geared toward Monks but which will help out anyone making Unarmed Strikes: Wraps of Unarmed Power, Insignia of Claws, Eldritch Claw Tattoo, Wyrmreaver Gauntlets. These may be of help if you're using the 5.5e Dhampir where the bite attack is explicitly a type of Unarmed Strike.

Berserker barbarian's Frenzy.  The attack is strength-based (only the damage is con-based), the bonus damage from frenzy is the same type as the base damage, and it explicitly works with unarmed strikes.

Hunter's mark doesn't help for all purposes, because it's force damage, not piercing.

You might also check out the piercer feat, although that seems silly and low value.

Also Enlarge/Reduce will increase the bite damage by 1d4.

I am playing a 2014 Dhampir (Tabaxi) Echo Knight Fighter (Tank), and can tell you that after low levels, the bite Heals, even if you were able to use 2d4 will not be enough to help with creatures doing much more damage in later tier of play.

Heck, even the Fighter's Second Wind which can heal much more than the Dhampir's Bite, doesn't really help much of the time.