Pregnant? or False?

My period is 2w 2d late. The day AF was suppose to come my doctor did a pregnancy test in after noom and came back negative.  1w late i did my own in morning and came back negative. 1w 3D late I did another in morning and I got a positive. at 2w 1D I did another at NIGHT and negativive. No idea what to think. Anyone else in the same boat. I keep having lower back pain. The whole week my period was due my lower abdomen was crampuy but not as bad as periods