discrepancy in pregnancy?

l, according to this app, am 30w,2d pregnant. If I look back at the glow app, which I used to track my cycles, i'm 33w,3 days. I used the same due date for both apps.

I had my last (that I remember recording) period in February, but I do remember texting my gf a negative pregnancy test 3/16. my positive test result showed 4/6.

At my last two growth scans they said baby was measuring big( I know u/s aren't always accurate). This is my third baby, and the only reason I ask is because I feel like I have no more room for this baby to grow. My stomach is stretched to the max!