(Bits and part of Info I have gotten from the Sanguinarius web site)

Some symptoms of real vampires can be  but may not be all of, nor must they all be present

 Being nocturnal , having excellent night vision, and/or sensitivity to bright lights/sunlight. 

Needing (not wanting) blood ( other then fetish blood play), To the point where it cause you to dwell upon it for. Ingesting it provides you with a sense of peace, relief, relaxation and burst of energy. You have a madding need to acquire it and drink it. You may feel like no matter how much you eat or drink other things it does not help. You become weak, irritable, and feel out of it if you do not drink it fairly regularly.

To some extent heightened senses, such as sense of hearing, smell, or touch;  Extremes are uncomfortable . You can hear things such as the buzz from a TV set or your computer (drives me up the walls) that other people can't hear, or have difficulty hearing.  

 A Beast, which you have difficulty controlling when it surfaces. Generally it will emerge when you are in need of blood or energy, if you become angered, frustrated. You experience emotions of any kind intensely and passionately; people remark that you can be melodramatic at times, though to you, it's just a normal expressing of your emotions.

some vampires have  psychic abilities and/or sensitivities, to energy or emotions etc. this is not true for all.  Also, a great deal empathy (sometimes extreme empathy, where they have trouble telling whether what they are feeling is their own emotions or someone else's). 

Psychic vampires, or psy (psi)-vampires, draw energy from others, and will become perky, animated, invigorated, possibly hyperactive . while the one they are drawing from will become tired, weaker, or disinterested much like the effects of drinking or not drinking blood . Many have have the ability to manipulate energies.

Other problems are migraine headaches; various gastrointestinal sensitivities and problems,  mood swings, depression, melancholia; a sense of separateness from those in "normal, mundane society"; above-average intelligence; possibly diagnosed with hyperactivity or A.D.D.

If you have many of these, then, before you  guess you are a vampire, I highly recommend that you get your lazy butt to a docter :-)