Positive digital negative line test plus spotting ?

Hello ... I just had a baby by c section 4 months ago .. last month I took a plan b a day after having sex becuz I’m not on birth control.. my period was 10 days late wen i got the positive digital but yesterday I took a line one and it was negative ... I been spotting on and off since the day I missed my period it just came back with light cramping .. could I be miss carrying