Had baby 3 weeks ago and have unprotected sex few times this week what are the chances I'm pregnant? I'm suppose to get birth control shot in 2 days..

Small. Chances are small but possible, especially if you aren't nursing. Some women will start to ovulate as soon as 2 weeks after delivery. Let your clinic know.
It's possible! If you and your husband don't want to have another baby right away, don't have unprotected sex. You can get pregnant after delivering a baby, before having a first period! most couples don't want to have two babies so close together. Ask your doctor about getting a pregnancy test before getting a birth control shot, and be certain to tell your doctor that you have been having unprotected sex.