I am 15, had my period for a year and a half and recently I have missed my period for about 3 months. Usually it is very regular. I also usually get bloody noses during the winter time, but recently they have been much stronger and frequent. It has been worrying me and today I got extremely dizzy. I eat very healthy, take yoga 3 times a week and bike regularly. There is no way I am pregnant. I also cut out dairy from my diet and thought maybe that could be a reason. Please help, I need some peace of mind

Sounds like two separate issues. The nose bleeds can be from several issues, the type of heat used in the house can lack moisture and cause nose bleeds in winter, ( common) or it can be nasal infections, or other health issues.

A visit to your doctor is needed to determine what.

I will assume you are not having sex, ( since no birth control is 100 percent) so the only way to say you are not pregnant, is not having any sex.