If u start getting symptoms of period does that mean u definitely aren't pregnant, or is there still a chance that u could be pregnant?

Take the test. If you want to know if you are pregnant, take a test. In today's world you do not need to wonder if you are pregnant or not based on symptoms. Pregnancy tests are available at any pharmacy and in minutes you will have your answer. They can detect a pregnancy 7-10 days after conception. The best time to take one is when you miss your period.
You could be. It is very common to feel like you period is about to start even when you are pregnant. This is especially true in regard to cramping and bloating. I would recommend just waiting to see if your period starts. If it doesn't take a pregnancy test. Make sure you're taking a women's multivitamin with 100% rdi of folic acid!