Have you tried lanolin? If the latch is good, discomfort should go away after a week or two. It did for me, but I used a lot of lanolin. As for breastfeeding positions, maybe try reclined breastfeeding for shoulders to relax or laying down sideways to put pressure off your tailbone?

Put a bit of breastmilk over your nipples after each feed and let it air dry, it really helps. Prop a pillow under baby so they’re slightly raised when you’re feeding to help with shoulder pain and prop yourself up as much as possible with pillows to help the tailbone pain. I get tailbone pain as well still 10 months in but it’s because I’m not supporting myself properly. It’s all gets easier the older they get because you can move around more.