Can you get Pregnant on an iud

So a few weeks ago I had a period on my iud which lasted almost 2 weeks and I had sex when it was almost over and after it ended and both time I had unprotected sex because I was on birth control with my ex boyfriend of 4 years the last few days I haven’t been eating a lot because I can’t keep anything down I throw it all up & I went to the hospital days after we had sex and they did a blood test for pregnancy and it was negative but a friend told me it might have been to early to tell after she saw me throw up when I hadn’t ate anything all day