period is different in color

Hi everyone...

I take the pill, but sometimes I do forget to take it.
Which means sex has been unsafe sometimes.
I've gained 4kg without any reason. (not just around the belly)
Since last month I've been taking iron tablets because my levels were too low.
I didn't dare ask my doctor if she wanted to do a pregnancy test...
My period has changed color, it's bright red now and lasts only 2 or 3 days. (usually 5-7 days)

A few weeks ago I had a sharp pain in the lower right side of my belly during sex.
I also get occasional nausea in the evenings.
My breasts feel a bit firmer but there's no real cup difference...

I was wondering if there's a chance I'm pregnant.
I also have cramps (the same kind I get when I'm on my period).

Thanks in advance,...