Re: Pain 3 1/2 weeks in, getting discouraged :(
your post brings back memories. breastfeeding my first dd, two years ago, was exactly the same. It gets easier.
I wore a nipple shield until dd was 6 weeks old, or for six weeks in total, I can't remember which. Give your nipples time to heal. DD went back to my breast with a little effort. I think it took a day or two for her to be really comfortable with the switch. But, it was worth it. By then, my nipples were healed and it didn't hurt.
Reading the La Leche League website really helped me. I read an article about how we eat hamburgers and how a breast in baby's mouth needs to be the same. Basically, when you eat a hamburger, you squish it, then tilt it up to the roof of your mouth. The bottom bun is eaten more than the top. Baby needs the same form on your breast.
The good news: breastfeeding gets easy and painless. By 4 months, baby can hold its own head and participates more. By six months, baby can put your nipple into its mouth. And, nursing baby #2 is painless.