My boyfriend has been taking testosterone shots once a week, and I guess that is suppose to lower your sperm count. Does it lower it or can it completely get rid of your sperm count?

And also, I've been really busy this past week, and have forgotten to take my birth control, but had unprotected sex with my boyfriend. Is there a possibility that I could be pregnant? I had my period a week 1/2 ago, but in the last couple of days, I have been bleeding very heavily and it is very dark red/purple in color. I know that implantation bleeding is suppose to be very light and pinkish brown. But I have also heard that if you have a large uterus lining that can cause dark and heavy implanation bleeding.

Is any of this true?