You are doing such a great job! And going by your baby's weight, he agrees! I also wanted to say that it took a long time for us to settle into a comfortable nursing relationship....about 3 months. I remember at six weeks when I was still dreading latch-on and becoming weary wondering if we would ever be able to get it together. My dd was also a strong sucker, they get more gentle as they get older. My letdown was/is also intense. It helps to break latch when it occurrs and let it drip (or squirt) into a cloth. Can you feel the letdown yet, I don't think I could at 7 weeks. Hopefully you can.
Also, varrying positions, especially on the side that is more sore, really helped us. My right side was a mess for so long, cracks that wouldn't heal despite a good latch. Go figure. I used the hydrogels on and off whenever I needed a little TLC and watcher her like a hawk when she was tired (which is usually when she would start doing the funky nipple suck). Also, and I know this probably isn't a great suggestion for everyone, but I used Motrin for pain when it got really bad, usually after a rough night of feeding.
I promise it will get better. Your baby is still learning how to nurse and will improve each week. I thought I'd never be one of the mom's who could stick my baby on my boob and not even assist with the feeding......now I am. You are doing a great job!