breastfeeding tips?

just had my baby a couple days ago and I'm breastfeeding. the first day went pretty well actually, she does have a weird latch but I think it's bc my boobs are odd shaped and huge. So it still hurts a little when she latches, doesn't matter how much she has in her mkouth. a second thing is I'm still in the early stages so I don't have milk yet.....how do I know she's getting enough. bc even after I feed her 20 minutes a side she still seems hungry but at that point my boobs are sore. also how will I know when my milk supply comes in??