If balance is a key issue for you and your DM there are a couple of provisions in the MM that you should bear in mind.
First, one way to look at it is, as the commenter above me put it, whether or not the transformation to becoming a full-fledged vampire is complete. You and your DM would have to work together to determine what were the conditions under which you became a vampire and how long ago it happened. Note that becoming a vampire from being bitten by another one states that:
A humanoid slain in this way and then buried in the ground rises the
following night as a vampire spawn under the vampire's control (MM 297)
This means that if your character were a "fresh" or recently turned vampire, you'd likely be a spawn and not a full-fledged vampire. It would probably be a long time before you can become a full vampire if you didn't have the means to take the position by force. This is because, as the born from death entry on MM 295 states that:
Most of a vampire's victims become vampire spawn- ravenous creatures with a vampire's hunger for blood, but under the control of the vampire that created them. If a true vampire allows a spawn to draw blood from its own body, the spawn transforms into a true vampire no longer under its master's control. Few vampires are willing to relinquish their control in this manner. Vampire spawn become free-willed when their creator dies. [my emphasis]
Even if being a spawn is not what you're going for and you only want to be a full vampire, you and your DM should remember that the bundle of negative traits that come with the positive ones can be played in ways to meaningfully limit your character (such as Forbiddance, Harmed by Running Water, Stake to the Heart, and Sunlight Hypersensitivity; MM 297/298).
Any time you have to enter a building, or go into the sun, or be near running water, your character could be severely gimped or face a skill challenge that no one else in your party would have to do. This may add some interesting mechanical and RP dimensions to your character. Ultimately whether or not that's enough to be considered an acceptable trade off for legendary resistance is up to you and your group.