2 periods!! in one month?

Do you just mean a little bit of spotting about halfway between two periods? It's possibly just ovulation - quite a few women get spotting when they ovulate (roughly 14 days after the start of your last period). So if that's about when it's happening, your doctor is right, it's normal. Also, you don't say how long you've been having periods for, but if you're still young then some irregularity in your periods is normal. Weight loss can also have an effect - though usually it's that if you're underweight your periods become irregular or in severe cases can stop.