I had a baby and after that I only had my period once. Now its five months later and I have not had my period ever since. Could I possibly be at risk?

Postpartum periods. About 5% of women will develop thyroid problems after a pregnancy. Breast feeding can also interfere with resumption of normal menses as can weight gain. And, if you are not using contraception, there is always the possibility that you are pregnant again. Please see your physician to see what's going on.
No period after baby. You could be pregnant, but it depends. Are you breast feeding exclusively? If so, this may prevent normal monthly cycles. However, it is not a very effective method of birth control. Have you been having unprotected intercourse? If so, yes you could be pregnant. I would recommend taking a home pregnancy test and following up with your obstetrician.