Your MW is a scaremongerer - I am quite cross with her too.
DS had a slight tonguetie, so slight that it was missed by 3 MWs, despite me asking them to check (DH has one too) - the breastfeeding expert was the one who found it by running her finger under his tongue. She said she could refer me then and there or we could see how I went with feeding. A couple of days later, the home visit MW asked me how it was going - felt like razorblades being sucked through my nipples and DS was taking around 2h for each feed (Lying down in bed, mostly) so she referred him to have it separated.
The paediatrician was lovely. He looked, felt it, said it was only a partial and that snipping may make no difference; or it might help. He said he'd seen full tongue ties separated that made no difference, or that made a huge difference; and the same for partials. Did I still want to go ahead? I said yes because I thought it could make a difference so it was silly not to try.
A sip of sugar water, a drop of novocaine (the stuff they use in dental anaesthetic), one quick snip with the scissors, a dab with cotton wool and 5mins later he was on the breast. Not even a whimper. No later bleeding, no problems, no infection and it made a HUGE difference (I had a survey thingy to fill in afterwards, presumably for statistics to show that even partial tongueties can benefit from being separated.)
I am SO GLAD I had DS's tongue tie done, I can't tell you. Feeding improved slowly but became much less painful as he managed to use his tongue better and he fed a lot more quickly.
A friend of mine had a DS with a worse tongue tie than my DS's - not properly picked up until he was 3 when I was teaching him to stick his tongue out and I noticed it. He was having speech problems as well, so they had it done then - general anaesthetic, quite a lot of pain, difficulty eating for a few days - far better to get it done when they're tiny babies.