so i beat the main Dawnguard quest, *vampires side* and i still cant make crossbow bolts or a dwarven crossbow, does anyone know how i can get/make the bolts and dwarven crossbow if possible?

You can't make bolts or better crossbows on the vampire side.

You can't if you side with the vampires.
Only Dawnguard members can craft bolts, & upgrade crossbows.

is it atleast *possible* to find a dwarven crossbow?

No.