I had terrible issues with my last baby. She eventually had a few little white places in her mouth, but not that tiny. Even though we didn't have classic symptoms, I'm positive we had thrush. I think I still deal with it off and on now. I had mastitis over and over, she was an awful nurser, and it hurt so bad. I had the funny color thing, and the burning, and the deep pain. Even the lymph nodes way up under my arm would swell, and I'd get the random lumps. Although, most of my pain is in the 3 places I got mastitis. It was awful. If I take iron, and watch the sugar intake, hydrate, and sleep enough, it all goes away. If that stuff gets messed up, then the right side starts hurting, then the left, and it just goes downhill from there.
She does have a lip tie. I always said there was something wrong with her latch, but it looked normal. Looking for teeth when she was nearly a year old, I saw that her upper lip is tied in 3 places. So, that explains that. It did get better as her mouth got bigger. One thing I would do is put my finger just under the nipple, and then, after her mouth was REALLY wide, I would flip it into the top of her mouth. She was able to take more in that way, and my pain would be significantly less. I would often leave my finger just under her lip to keep things pushed where they needed to be. She, too, gained normally.
I was really annoyed with the doctor's help, too. The lac consultant was confident it was thrush, despite not having classic symptoms. She said, especially by your fourth baby (in my case), your body is just run down and funky things happen. I dunno, but I do know that I was super relieved when one day around 8 weeks I suddenly realized that nursing wasn't toe curling painful anymore.
You can do it. :)