Help please

Hey guys. So I just turned 18. It seems that my period is really really messed up. I talked to my doctor, well the nurse practitioner, today and they want me to get blood tests because this apparently isn't normal even though the one said it was. Mom isn't making me do it because she knows I don't trust the lady who checked me. I would have been much more comfortable had it been my actualities. Anyone have any advise for me? l really don't know what to do... Also I am nonsexually active. So I'm not pregnant...