I figured I'd throw in my experience...my 2nd had major tongue tie and we had breastfeeding issues the entire time-namely, major major pain for me. For MONTHS it was agonizing. We saw probably 5 LCs and no one figured out the problem. It wasnt until we found our current ped that she noticed it and said it was so friggin obvious, she couldnt believe that no one had noticed. By then, I had weaned her (she spent 3 months yanking, biting, pulling away and I just couldnt take it anymore) but it was good to know. We made sure our next babe didnt have the same issue.
Anyway, she actually developed speech issues because of it, we had her evaluated by a speech therapist and she agreed it was due to the tongue tie. Again, it was very bad-the flap of skin that holds the tongue was all the way up to the tip, held it down very tightly, and she couldnt stick her tongue out past her lips, and it had the heartshape to it even then. As a seperate issue, she also had sleep apnea and huge tonsils, so in a way we got lucky-we had her tongue clipped while she was under general during her tonsilectomy. The surgery fixed both problems and now she's a normal 5 year old.
On a side note, at first, I could NOT find a doctor willing to do the clip with any sort of sedation or even lidocain or something similar. I put it off as long as I did because I refused to have my dd go through that at her age-she was already 2 by then and I didnt want her scared of the doctors or to go through the pain. So I was very careful to make sure my next one was ok right off the bat, and luckily she was