He was told he was sterile by a sperm bank, im pregnant?

I didn't get my period, tested positive, I'm showing some symptoms besides morning sickness but I'm only 4 weeks in.

I'm going to test again tomorrow cause he wants me to, it will ease his thoughts cause he still thinks he's sterile. He tried donating sperm once, and the people there said hes sterile. I'm so worried it'll be a BFN.

i heard about chemical pregnancys and im scared. I've been so so so excited for this baby.. He's the only person I've been sleeping with for the past year.