My ds had an undiagnosed ptt that ended our bf'ing relationship by the time he was 6 weeks old.
My dd who is 7 months also has a ptt and had an upper lip tie. She had her tongue snipped at 2 weeks old but there was no improvement in her feeding.
I resigned myself to painful/uncomfortable/lengthy feeding and got domperidone and took fenugreek to keep my woeful supply up. Also I started supplementing with 3 bottles of formula/donor breastmilk a day.
As she got bigger/stronger I was able to cut the bottles down to 2 a day.
I then found out that there is a high likelihood of the ties reattaching without proper stretching and aftercare, something the practitioner who snipped her tongue told me was a myth. Also I found out that there is a higher rate of success getting the ties lasered by a dentist.
I had her ties lasered at 4 months old. Even with proper aftercare and stretching her tongue tie reattached.
Breastfeeding is still uncomfortable at times, didn't help that my dd got her two bottom teeth at 3 months lol. But she's a lot quicker at feeding these days. She still has 2 bottles of formula a day (350mls total). I'm happy with that as when I've had enough of breastfeeding it'll be easier to wean her onto a bottle as she already takes them.
I will look into getting both my ds and dd's ties released when they are a bit older as they can cause all sorts of teeth problems.
I just thought I'd tell you my story so if your tie release is unsuccessful it's not the end of the world and breastfeeding is still possible.
I wish you the best of luck, I know how physically and mentally draining the whole process of this is and something as natural as breastfeeding being so hard is a bitter pill to swallow especially if you are determined to breastfeed, or in your case have had success in the past doing it. Feel free to pm if you have any questions.