If your really worried take another test and see what it say then make a call to your OB but to answer your question yes you can have a light one in your first trimester.
It's not possible to have a period and be pregnant. Also if you were pregnant you wouldn't be feeling movement yet anyway, that wouldn't come until you're about 18-20 weeks along (for your 1st).
Most likely gas or constipation is the cause. See your doctor if you're concerned.
My best friend and a couple others I know had periods until about 5 months into their first pregnancy so yes it is possible. Not as common but it does happen
You CAN NOT have a true period while pregnant. You can have vaginal bleeding. If you had a true period while pregnant, you would miscarry. A period is your uterus contracting and shedding the lining. #1 your cervix closes and has a mucus plug to prevent anything getting in or out. So actual uterine bleeding that presents out of the vagina would be a medical problem while pregnant and it means something is wrong. #2 your vaginal walls and cervix while pregnant become very blood enriched which can promote bleeding with irritation from sex, wiping, or anything else. #3 when the egg implants itself at conception the hcg and progesterone it releases halts your periods because, like I said, if it didn't you would have a miscarriage.
My mother had her period the entire time with my brother and I. She had the whole week of bleeding around the same time every month. She didnt find out with my brother till she was 6 months along because she didnt think it was possible. It is possible, just rare.
Good explanation Factorymomma! It saves me having to explain, lol!
http://www. thelaboroflove .com/articles/can-you-have-your-menstrual-period-while-pregnant
My mom had her period and got pregnant because it would have been twins. One egg died, the other lived. Very confusing. But as for movement....... the baby usually is around four months along to actually be able to feel its kicks. If you've been having your period every month I highly doubt your pregnant. And if you were far enough along to feel the movements then a pregnancy test could tell if you were pregnant. It could be gas, talk to your gynecologist or doctor.