[Eternal]

If your last period was the last week of October then it's only been a month. Periods have a cycle of about 28 days on average, but it varies a lot, especially since you're young and not on any birth control. They can be late for a lot of reasons. Stress, change of diet, change in amount of exercise, etc. When I was 16 I actually went a couple months without a period but everything was fine. Always use condoms, it's not worth the risk and the fear. I also recommend you talk to your mom about getting birth control. If you're going to have sex, be responsible. Use protection and have a plan with your boyfriend in case you get pregnant. Abstaining from sex is the only way to completely prevent pregnancy.