I'm 31 and recently had issues with the sex drive thing. It pretty much went away when I was pregnant with my dd, who is now 5. Then I had issues with my vagina that were surgically corrected when she was a year old, so it didnt hurt to have sex anymore, but I still didn't really want to. I was on the pill, and it made me very angry and not want to be touched, and it's been over a year since I went on it. I decided finally that I was just going to have sex when my husband suggested it (not all the time, but most of it) and see if that would help. He's very nice in bed, always wants to make sure I get my cookies, too, so it's not like it was a hardship, but I did have to fake it a few times. It's always a hurdle for me to get from being comfy doing my thing, to going all the way to the bedroom, getting undressed, having sex, then going back to doing what I wanted in the first place.
It seems like in the last couple of months, my sex drive has REALLY taken back off, to the point where it seems like we're having sex all the time. (well, to me it seems like a lot, to him it seems like just the right amount, LOL) I haven't enjoyed it this much since we first got together, and I think it's just because I made up my mind that I was going to start liking it again and just did it. Maybe it's because we're doing it more in the dark so I'm not as self-conscious, or because it's more after we've gone to bed so I'm already there, or because I'm letting him go more "downtown" so to speak, I don't know. But for a few years, I thought I was just broken and would never really want to have sex again.
I don't know if any of that was helpful, but I hope that something will work for you! I can't imagine that 2 1/2 children are really making you feel sexy, and being tired is probably another issue. Good luck!