This might be a long post, but I am desperate and need some help!

My last regular menstrual period was Feb 5th - the 12th. My S.O and I have had sex (unprotected) on the 13th, 18th and 28th of feb. On March 2nd, I've had dark brown spotting for a day (really minor) and stopped. I missed this months period and still hasn't gotten any sign of having it. I took numerous pregnancy tests and it all came out negative so I told myself, maybe I'm testing too early? The last pregnancy test I took was this past thursday (March 15th) it was at my doctors, and it turned out negative. Therefore, I was suuuper sad because I was having some symptoms that I had when I found out I was pregnant with my previous kids. Since yesterday, I've been having mild cramping all day off and on (from 0-10 I would say around 4) but this morning I woke up and went to use the bathroom (still no sign of my period) and the cramps are still here. What should I do? I really dont know whats going on with my body. Its not like I've been stressing or anything. My doctor told me on thursday that because I got a negative test but having all the signs of being pregnant, she wanted me to go to the E.R just in case it ended up being an ectopic pregnancy. However, I don't feel like I'm having an ectopic prrgnancy, I just think it was a little too early to detect my HcG hormone. Anyone else went through something similar?? I live 52 miles (almost 3 hours) away from the nearest E.R/Hospital and the doctor here is only a little clinic and doesn't provide a lot of things that the big hospital can. I have 2 kids with me and can't find anyone to help watch them while I drive 3 hours away for a check up. Doctor also offered to fly me out by helicopter, but I can't because I have my kids. My SO just left for work all the way on the other side of the island.

Sorry for the long post but i'm desperate for help or advice. Thank you all so much in advance!!