Ok, here goes:
1. You cannot get your period when you're pregnant. You CAN get spotting and / or vaginal bleeding, which is a reason to immediately call your GYN. It can signal an impending miscarriage or other problems.
2. There are no symptoms that can tell you whether you're pregnant or not. We're girls. We have hormones. They do weird things. It sounds like you cycle has just changed a little bit, but talk you your GYN about it. That's all their is to that.
3. You got it right - you should take a pregnancy test. It will give you peace of mind. You can also get a blood test from your doctor.
4. If you haven’t started taking care of your sexual health on a regular basis, I suggest that you get started right know. You need to see a GYN, and get a full STD/STI screening besides a pregnancy test.
5. In the future, use a condom! It's a heck of a lot easier to prevent this type of problem. If you don't take seriously the risks of an unplanned pregnancy or STD, than you may need to reconsider whether or not you're ready for sex.
Ride it like you stole it!