Spotting..?

So let me start this off and say there is absolutely no chance of pregnancy. None.

I’ve always had weird periods, months without it, a couple months with it. But the past three months I haven’t had a period... twice a month I’ve been getting very light spotting and major cramps. I’ve asked my doctor and her response was “well let’s keep an eye on it for a while.” But now I’m stressing. I’ve googled it and pregnancy, stds, and cancer all come up. I’m a virgin, so I’m not sure. I’m also 23, overweight but have been in the process or losing weight, and other wise healthy.