My lg had a very tight posterior tongue tie, she did some damage to my nipples, cracked and bleeding and I got mastitis twice. I'd consulted lots of midwives, my GP had seen me cos of the mastitis. It took nearly 6 weeks to find out she was tt, the NCT breastfeeding counsellor identified it and when I went to the GP for a referral he looked in baby's mouth and said she wasn't but because I was so determined he would refer me! I logged on to book an appointment online and it was going to be another 3 weeks. I asked the NCT bfc and she recommended a private midwife/health visitor who was trained to cut tt, she came to out house the next day and cut it with a pair of surgical scissors (I couldn't watch, but my husband held her head while it was done). My lg then had to relearn how to bf, she'd had a lot of bottles of formula by this point and my milk supply was going down, even though I was expressing. I took her to a cranial osteopath which I swear helped as she started clenching her jaw when feeding, almost biting me! Ouch. At 8 weeks old the cut under her tongue had healed, but feeding was still really painful, I was on the verge of pnd and so decided to give up trying to breastfeed, but not wanting to get mastitis again I put my lg to my breast to get a little bit of milk before giving her a bottle, I relaxed and it started working. It wasn't perfect every time, but I bf her until she was 10 months when I went back to work - I worked hard to get my milk back up and she just had one bottle of formula day.
It's so bad that different areas have such different views on tt. My sister's lb was anterior tt and they wouldn't cut it, said it would break when he started spoon feeding - it did but meant he had to have a bottle as he wasn't gaining weight.
My sister-in-law wasn't having problems with bf, but it was her second baby and she knew what i'd been through, identified the tt and in her area they cut it for her straight away.
Definitely try the tongue exercises as I was recommended to do those after she had the tt cut to stop regrowth. If it's affecting your happiness/mental health then keep on at them or find someone to do it privately. Take care.