Stop with the zombies and vampires already.
No, really, stop it.
The undead are the new cardboard-thin character- and plot-props formerly crafted to look like cowboys and indians, or gangsters and G-men. Unless you have something unique to add to the concept of the undead, or a story that can only be done with the shambling deaders DON'T USE THEM.
If your character doesn't seem strong enough as a human, making them a vampire won't fix the underlying issue - that you've written a weak character.
The saddest stories are otherwise good fiction saddled with the mouldering undead for no reason, discouraging serious readers from accessing an otherwise entertaining story. Would Moby Dick have been improved by a ship of zombie whalers? No.
Write your story, make it all it can be, and avoid the lazy temptation to insert overdone, tired genre conventions in it.