You had an abortion two months ago and I'm assuming you began the pill after that, right? If so, your body is probably just adjusting to all of it. It takes some time for the pill and your body to get in the groove so to speak. That's why they say to use extra protection for at least a month when starting the pill (because until it's regulated, you are still susceptible to pregnancy). If you've gotten to the week of different colored pills and you've only spotted, it's probably the adjustment. The pill lightens periods significantly in some people. If you're worried, ask the doctor about it.