I CANT BELIEVE IM PREGNANT AGAIN w/ 4TH BABY😒😩🤦🏾‍♀️

So i realized yesterday while at work that my period hadn't come on yet. I talk to my sister about it and she is trying to reassure me that it's probably just late. Because i just had a baby in March of this year. BUT she tell me to take a pregnancy test anyway just to ease my mind.I take the test and of course it comes back positive. My baby just turned 3 months on the 16 HOW TF DID THIS HAPPEN. Not to mention i had another baby in October 2015. Im so confused i love ALL my kids with all my heart. But a 4th baby i just dont know im not even married to my boyfriend and we have two boys together, i have a little girl with another man. This would be my 3rd child with my boyfriend. UGH, im so confused right now i just want to do the right thing!