Yes you can still be pregnant both times when I was pregnant I was on my periods .I now just tuk 3 test andthey were negative went to the doctors as I'm feeling sick in the evening and bachach she refferd me for blood test now waiting till monday to find out
I don't think so you can be pregnant as you have negative pregnancy test and now your period has started. But still if you have any doubt then you can take blood pregnancy test and also an ultrasound.
Its possible to have your period while pregnant. I highly doubt you are if the tests were also neg, but if any doubt, schedule an appointment with your doctor.