Has this happen to any one!?

Hi ladies

Ok so this month I’m late 6 days according to the app. My period started last month June 13 and I should of got mine this month but haven’t yet. I did get my period last month about one week earlier than it should of had. I’m not all about tracking my cycles I have been nursing my son of 22 months. Here and there. But we been trying to see if we can conceive so we can say that will be our last one. (Don’t Judge me) so we had sex during my period. For some reason it start off light not heavy so on my cd 3 I had sex. Then after that it started to to flow a lil bit heavy after that my period was gone my cycles are usually 6-7 days. But during my period I was feeling sick for about 2 weeks just nausea and lower back pain. Now the nausea comes and goes. But the lower back pain is still there. I’ve taken pregnancy test of all sorts like anyone who’s trying would do. I had seen faint lines and then all negative test even the digital one. Now I don’t even know what’s going on. Has any one gone through something similar? I have no pjs symptoms just a bit nausea when I’m hungry or after I eat. But some craps and pulling on my stomach. I haven’t went to my ob dr yet he closed his practice so I need to find a new one.