Is it possible to be get pregnant having 5 days before ovulation?

i had a miscarriage last summer and since then my cycle has been so irregular, last months cycle was 25 days. this month my period started on the 13th may and i stopped the next day, then bled on the 15th then stopped, and slept with my boyfriend on the 16th, for the last 2-3 days ive been throwin up, on saturday (21st) i was having awful pains right on the bottom of my tummy, im still getting them every so often now, my appetite has gone, i feel full after a few bites or just smelling the food. i know its very soon for signs but with the baby i miscarried last summer i was having sickness from a week after and pregnancy tests were showing up positive and the pains im getting are the same as when i found out i was pregnant with my 18 month old daughter. the doctor said i might just show signs early. is anyone good with dates? can you please help me out