need help.....

ok my fiancee and I have been trying to get pregnant awhile. when we first got together my af came on the 11th every month. sometimes a day or two before or later. since we.started trying my period was always late but would come the last week of the month. the past three months I had very light bleeding. it was enough for a pantyliner. that is not normal. also went through a stage where I was craving things, feeling sick to my stomach. I also gain in the three months about 15 pounds. we took three hpt tge first one said neg the second one was inconclusive and the third looked like it had a very faint line saying positive. not somewhat to think I went to the Dr and she did a urine test that came back negative she also had a blood test done and it said negative. but couldn't explain the.symptoms or the tiredness. my fiancee cousin says she thinks I am, even his family has asked him if was do to my weight gain. it isn't like normal all over. if you look at my stomach it looks like I am could I be pregnant??