Why is my guy constantly trying to get me pregnant?

Okay so my guy is constantly telling me how he need to gone head and get me pregnant. I already have a 2 year old and I am trying to finish school Im nearly complete but I cant be successful like I want to if I was to have 2 kids right now financial wise I don’t need another one and he knows that. So the other day as we were having sex he came inside of me. Im on the shot but I still didnt want him to do that. Yea I know all about safe sex but sometimes things happen. So he did it anotha time afta that and I was furious. He tried to play it off and say that he didnt come yet but I just know he did. So I have to go to the doctor and a few for anotha shot. and he tells me to miss that appointment cus he wants me to have his baby. Ugh, we are crazi about each other but I’m not ready for any more kids at this point. So how do I get him to understand that. Because everytime I say no im not having a kid by you just now. He acts as tho he dont hear me then next thing you know we are making love and he does the same thing. Oh yea yesterday when I put on some pants he was like that ass is fat imma have to put a baby in you!! Im starting to think he doesnt want anyone else to be with me if we was to be apart and therefore he is trying to get me pregnant so I can stay his.ADVICE PLEASE…