I didn't really choose to quit, my milk just dried up despite everything I tried. But yes, we breastfed for 10 weeks and then switched to formula. My daughter like yours had a short tongue (I'm assuming that's what you mean by a short frenulum, rather than a tongue tie, as those you can get clipped). She also had some other structural issues in her mouth which made it difficult for her to latch and she was born early term (37 weeks) so didn't have a strong sucking reflex either and it was a challenge to get her to eat anything for the first month. I also have flat nipples to top it all off. I had no idea any of these things could even happen, so was totally unprepared for how to try to work around them (we saw loads of midwives, HV's, breastfeeding counselors and they also struggled to get my daughter to latch). The end result being that she had a lot of weight gain issues because she just couldn't eat very effectively and I tried expressing to see if I could up my supply and was expressing 6 hours a day in the end (6 whole hours!). But literally I was getting drops and then finally nothing no matter what I tried. So we switched to formula.
I don't regret it at all and I feel like under the circumstances it was the best possible decision. She still struggled to latch and feed from the bottle until about 5 months, but because we didn't have to deal with the supply issues that her latch caused, it meant she was able to put on weight because I could always make an unlimited supply of formula. For us, it was the best possible decision, even though I'm glad I chose to BF her when I did and I'm proud we made it 10 weeks. But ultimately, yes, I'm happy with how everything turned out in the end. I never had anyone make me feel bad for formula feeding and I know there are people out there who will say things, but I do think that is the exception rather than the rule. Most of my friends BF their babies until they were 2-3+ and same for many of the groups I went to, but everyone was supportive. If anything, I got more negativity from medical providers for trying to BF because my daughter struggled so much. They would have much preferred that I'd switched to formula much earlier than I did and were quite unsupportive of my choice to BF (When I was at the hospital and asked for help with her latch, I had one midwife storm in, literally slam a glass bottle of formula down on the table, and tell me, "all my kids were formula fed and it was good enough for them, so it will be good enough for yours" WTF?).
I think if you want to BF and you can and you aren't in pain and you just need more support and you can get the thrush cleared up, hang in there a bit longer and get to a BF group or counselor to get some extra help. But if your heart's not in it, don't feel guilty about stopping either. I do plan to BF my 2nd (I feel like, different baby, different situation, no reason to assume it wouldn't work), but I have a lot more confidence next time to know when it's best for me to stop if the same issues develop again, because I know it will be okay. It was definitely the best decision for us. If it's the best decision for you, then trust yourself. Whatever you decide will be what's right for you and your baby.