Hey, I just became a vamp with these three mods and I got really big attribute boosts, for example destruction +20 and +30. I thought this was very weird, could this be a bug?
Thanks in advance

No, those are actually the bonuses to stats/skills from vanilla Morrowind, http://www.uesp.net/wiki/Morrowind:Vampires.

I take it you have been infected by Aundae Clan: being the "mages clan", they have an extra +20 to Destruction on top of the basic +30 every vampire gets.

Okay, thank you . It is weird though jump from 57 to 107 :S