Could I be pregnant? HELP!!

After being on Prometrium for 3 months, I have been getting my period every month as I am supposed to (was irregular) and the prometrium is just helping give back my period regularly. Normally I would start the prometrium and get my period the next day or at least start spotting. THIS MONTH, I am 5 days late as of today and do not have so much of an appetite. Any advice or suggestions?