Possible pregnant????

Ok back story baby's 10 weeks. Had sex maybe twice after 4 weeks. Once with condom, once without but pulled out.i was EBF at the time. Then at 6 weeks I got IUD placed. Stopped BF at 7 weeks. Had ultrasound to check IUD placement at 8 weeks. Bleeding on and off since IUD. Have had unprotected sex since 4 days after IUD was placed.

Today I went to drink my coffee and I feel nauseated and sick. Happened once about a week ago too. Hubby joked oh your pregnant again since I was very sick with baby. Is it possible???? Wouldn't the doctor or ultrasound tech see something? They said IUD was perfectly placed. Wouldn't that it be too soon since IUD ultrasound for me to be just pregnant and getting sick? I was 4 months pregnant before I got sick the first time. I do have a cheapy home test left but idk if I'd still have HCG in my system from before.