My Baby Will Not Sleep In His Crib

My baby is almost 7 months and he still sleeps in his rocker !! At 6months my plan was to transition into his crib but he just hates being laid flat ! The dr keeps reminding me of SIDS and it's freaking me out, plus he's getting too big for his rocker anyway. He won't sleep in his playpen either. I really am not sure what to do. I don't even know how to put him at an incline with it still be considered safe😔