Chance of pregnancy?

I finished my last pill pack on the 18th of april had my "period" as you can see on the calender....i did not start a new pack since we are ttc we've been bd actively fingers crossed. Glow predicted my period on the 23rd of May but i only spotted for the 3 days i marked i never got a full blown period i did a pregnancy test on the 26th and it came back negative. And i've been feeling nauseous and threw up a couple of times.. My question here...is there a chance of pregnancy or just my body regulating back after stopping the pill? Sorry for the long post. Thanks