Do you think I’m pregnant?

I’m 3 months PP and my cycle hasn’t came back maybe because I breastfeed on demand. I was feeling a bit nauseous on Sunday night not sure if it was over post nasal drip since it happens to me but it made me panic that maybe I was pregnant. Next morning I tested & it had been 3w 1d since I had sex & it came back negative. I haven’t felt nauseous or nothing out of the ordinary but my sinus congestion is still there. Do you think I might be pregnant? I have an appointment right now so I’ll tell them to test again. Hopefully I’m not😩