Lost virginty about a month ago and mom wants to take me to obgyn for the pill. with a papsmear exam, will the obgyn be able to tell if i have had sex?

No: Not unless there are sperms. But what's really going on. Your physician is supposed to be your friend. If you are part of a "traditional culture" in which a physician certifies virginity, you have my sympathy; this would be totally unethical for a physician in the US. If you are indeed 20 years old, you're an adult and you make your own doctor appointments. Be appropriately assertive. Best wishes.