Even though there's so much pain, from the sound of it, you are doing SO great. It is unnerving not to know exactly how much LO is getting but plenty of dirty diapers mean plenty of milk is going in
My daughter had an awful shallow latch that reduced me to tears. I never dreamed I'd have any trouble at all breastfeeding! My son took to it naturally and I wasn't ever sore at all with him and ended up using the Lansinoh ointment on his tush. Just because I myself knew what to do meant nothing to my newborn daughter. My daughter hadn't a clue what to do other than to suck away which left me with blistered, cracked and bleeding nipples that made my toes curl, my eyes cross and I dreaded feeding her.
She would often get frustrated at my boob at times. I swear it was as if she was attempting to fight it, frailing her lil arms around before pulling off and screaming at it. It seemed like we fought and fought to get her latched on and then POP off she'd go, screaming
I found it best to put her on my shoulder and pat her. Sometimes she'd burp and that had been what she needed, sometimes not but it soothed and calmed us both down before tackling it again.
Afterwards I would swap sides, sandwich my nipple between my index and middle finger and attempt to shove as much as possible into her tiny mouth. Sometimes I'd have to work and work at it before FINALLY success! Sometimes I had to leave the living room, go to a darkened bedroom lit with a small nightlight and turn the fan on for background noise. Sometimes all the noise and lights (TV, other family members) seemed to overwhelm and upset her.
It took about 3 weeks before she finally got the hang of it and I wasn't in tears anymore. Just remember that while some babies are great right away at breastfeeding, others have to learn. It's new to them too and you aren't the only one upset at times
It WILL get easier. Then you will remember how much of a bother washing, mixing and warming formula actually is compared to whipping a boob out. I HATED it when I went to work and had to switch to formula with my son. Nothing like staggering in the middle of the night into the kitchen to fix a bottle to the tune of a screaming baby
BTW, I also would squeeze a bit of breastmilk out onto my nipple and rub in. Breastmilk is great at healing (I've used for diaper rash, gave some to a friend for pink eye which cleared right up!) I've also used coconut oil to moisturize my nips.
No matter what, as long as you and baby are happy and healthy, that's all that counts.