Oh, you poor thing. Sounds like hard work. My LO is now 17 weeks old and still bfing her. I had mastitis and remember those first few weeks and how painful they are. I did find that getting baby in to the right position helped. Have you tried the rugby tackle position. Also the best midwife tip I had was once baby was latched on hold her firmly against the boob. That helped to stop her slipping off - that was the cause of my pain. Rather than a bad initial latch it was her slipping off, but still sucking and me not wanting to change her. So, if she does un-latch, make sure you take her off and re-start her.
I called the NCT breastfeeding help line a good few times for similar questions...they were really helpful,
Really good luck. The first few weeks are so hard work, and you're doing such a fantastic job. Keep it up if you can. And things really do get sooo much easier. To the point that you wont even think about the latch on. But I know, those days seem a long way a way now...
All the best xx