Thanks for coming here and sharing your fears. First thing you need to do is take the test! I can't tell you for sure if you're pregnant or not pregnant. Even you can't know that for sure. Yes, I know I'm not telling you anything you don't already know. But, I think you need to hear it: take the test. I was 20 years old and 2 weeks late, and dreading taking the test that would possibly confirm my fears. I finally took the test at 14 days late for my period.
I'm so sorry that you've lost your mother. I lost my mom a couple of years ago, and even at 36 I was not ready to lose her. I did have the advantage of having my mom around to help me through my unplanned pregnancy. I'm sorry that you don't have your mom around to help you through this. I know that there are no good replacements for your mom, but do you have another woman in your life that loves you and would want to help you through this? I bet you do. I have learned to lean on friends. And I have learned that I have women friends who are willing to help me through life's rough spots.
Please take a pregnancy test. There is a chance that you're not even pregnant, as women do have missed periods that are not caused by pregnancy. If you are indeed pregnant, please do let me know. I'd love to offer advice and support you!