Kinda long but need advice pls. Keep negative comments to yourself.

So when i got pregnant i had just broke up with my bf and got with somebody else. Obvious stated, idk who daddy is. Im back with my bf and have been for 98% of the pregnancy. It has been a rocky road and now that im a few weeks away mt bf is growing more and more hurt and confused as he wants her to be his. Along with this he has asked me to do a dna test while pregnant so if shes not his hes not suprised at birth along with the rest of his family. I dont know what to do, ive heard amniocentesis are very dangerous as far as miscarriages. I personally don't think the results would be back before she was born anywase as i only have 5 weeks left. So questions are is this risky to my child and would the results be back before she was born?