I am very new, but am experiencing the exact same problems.
My son is almost 6 weeks old and we are still having latch problems, but it is getting better. He just won't open his mouth very big. Babies are very smart and I try to tell him "Ow, you are hurting Mommy" and "Open big for Mommy" then open my mouth big and stick out my tongue. When I say ow, he actually seems a little gentler when I pull him off and try again. They watch us when we are feeding them, and note our reactions. I haven't gotten him to open big yet, but I'm still hopeful!
The sore nipples- Last week I almost gave up because of the sore nipples. But, I went and saw a lactation consultant and she gave me some advice. Of course, my son performed a perfect latch for her so she wasn't too helpful, except in telling me I have a quick let down (highly frustrating as well when lo sucks very hard to get the "fast flow") and some tips for some of the problems I was describing. If you do a search for assymetrical latch, that may give you a new way to latch, that is definitely helping me! I am wearing tank tops with support bras, otherwise, if anything just rubs against my nipple (I don't care how soft it is) I want to scream as then my nipples harden and the pain just gets worse. I am also using warm wash cloths (the babies - they are softer) to gently wipe my nipples before putting on the lanolin. I can't give you a reason why exactly, it was just a spur of the moment idea, and it made me feel better. Just be sure not to let cold air hit your nipples while damp. You'll be back to square one. You can also express some milk and dab it on your nipples and let them air dry. I do that when I can allow my breasts to hang out in the open.
I found a support group that meets next Friday and I will be going to that, as the assymetrical latch is helping, but some of the holds are uncomfortable, especially as long as lo wants to bf (sometimes an hour). Hopefully, I will be able to get some tips.
I hope some of this helps - I know it's hard, but I know it is getting better, too! Keep trying if you can!