Possibly pregnant?!

I had a miscarriage in sept 14 and again in jan 15. Both losses were devastating to me and my bf. I am terrified to get pregnant again and lose another baby, but at the same time there is nothing I want more than to be pregnant. My periods after the miscarriages have been regular, but this month is different. According to my period tracking apps, I am anywhere from 2-5 days late but all my tests are coming back negative. I don't know what to do and don't want to get my hopes up just to find out I am just late this month. I had light cramping on Monday but nothing since then. My nipples are a bit sore and have turned slightly darker (tmi I know. Sorry). Any advice?