Help!!

I'm on cycle day 42. My average cycle is 32 days and my period was supposed to arrive the 9th, but now it's the 19th. I had sex on cycle day 36 and I had protection at first, but it kinda just left the picture because we were too stupid. He pulled out a minute before. I took a pregnancy test on cycle day 40 and it came out negative. What do y'all think?