trying for our 4th after 5 yr IUD

My husband and I are trying for our 4th child after having a Mirena taken out 3/16. Had some bleeding for 3 days after the Mirena removal and NOTHING. Our first unprotected BD was 4/2 and has been almost daily since. DH has HIGH sex drive. 4/12-4/14 battled some nausea and headaches off & on. Could I be pregnant? I've never had a regular cycle so this is really hard for me to track periods.