baby sleeping on her side?

My 2 week old sleeps in a co-sleeper in the middle of my bed I barely sleep because she spits her milk sometimes at night and she has almosted choked 3 times... So I put her on her side I put my arm next to her so I'll feel if she moves to her tummy... I'm scared of putting her on her back... Is it really bad that I put her on her side?