Pregnant or Paranoid? ?

I had protected sex almost 4 1/2 months ago and I'm scared I might be pregnant. That was my first time having sex. My stomach keeps growling and I'm not hungry and I keep feeling bubbles which could be trapped gas but idk. For the past two days I have been really tired and my back has been hurting. I thought that these symptoms would have came earlier but I'm just now getting them. I also have had my period each month after I had sex but my last period was light. PLEASE HELPP!