Question about Provera

I believe I am pregnant. Two or three faint positives but a negative today. So that's what is leaving me questioning. BUT, long story short I had a chemical a few months ago and doctor gave me Provera to induce a period but I started one naturally. She gave me this so we could run blood work ok the second day of bleeding. NOT SAYING I AM GOING TO TAKE IT, but if I did take it and I ended up being pregnant, would there just be no bleeding? I've read online it was used to "test for pregnancy" as in, if you bled, you weren't pregnant. If you didn't, you were pregnant! Others say it can cause birh defects and miscarriage. I am going to call my doctor before I take any actions, but I was just curious of anyone else's experiences with this