Hello,I'm Taking Iron Pills. Can They Delay My Period? It's

Hello,I'm taking iron pills. Can they delay my period? It's been a little over a week. I feel it's coming. I get bad cramps and back pain but no blood yet. I had unprotected sex last week on Sunday april 24 but then took morning after pill. Took a pregnancy test on Sunday may 01 but came back negative. It might be too early to get the result. Can I really be pregnant? I was supposed to get my period on the 25 april