Could stress cause me not start my period on time. My periods haven't been on time all the time after I had my daughter and I can't afford to get on birth control yet and my boyfriend and I don't use condoms.

You . You can get free condoms at most clinics, such as planned parenthood. Hormone changes can cause late periods, but since you are having unprotected intercourse then you should take a pregnancy test to be sure. Please be seen at a clinic and have them advise you; there are many means of free birth control if you desire it.