Nursing while pregnant struggles

Is anyone else nursing while pregnant? I am 10 and a half weeks pregnant and still nursing my 7 month old but am running into issues. My nipples are killing me, I get very nauseated while nursing and worst of all my milk supply and rapidly disappearing. Does anyone know of anything I can do to help with these problems!? I really want to BF my son until he's a year and I'm an emotional wreck over almost losing my milk this soon!