Could I be having an ectopic pregnancy?

one week before I was suppose to start my period I had light spotting for 2 days, and now I am 2 weeks late. I am having pregnancy symptoms, like nausea, and vomiting , tender breasts, heartburn, back pain and headaches. I took a hpt yesterday and it came back negative. I had a tubal ligation 5 years ago and that is why I am concerned about a tubal pregnancy. I have been having pain on my right side, not unbearable but very uncomfortable, and that has been going on for a week. My periods are usually on time, and I have never been this late before without being pregnant. I don't have insurance, so I was wondering what are the possibilities of this being a tubal pregnancy, I don't want to go to the er if it isn't likely, and what are other symptoms of a tubal pregnancy?