Jealousy

So, I have a boyfriend and a girlfriend. Currently I'm 18 and I'm a senior, they are 20 and 24 and have multiple jobs each. We live in different states because they are currently living with his parents while we save up money to get a house, and his family doesn't know about me yet because if they did, my bf and gf would be thrown out. Once we buy a house I will be moving in with them. We plan on buying a house in the state he lives in because my gf and i dont have a lot of family, but all his friends and family (he has a lot) live there. We are poly, and we love each other equally, but I can't say that I'm not jealous of my girlfriend. First off, she gets to live with him first even though she came into the relationship 2 years after my boyfriend and I started dating. This means that they have created a bond that even my bf and I don't have, and they get to talk way more and actually spend time together. Second, she accidently got pregnant. Even though I'm young, I want a baby. I spend a lot of time with children, including babies, while babysitting and volunteering, and I know that I want my own child more than anything. It doesn't help that she constantly complains about being pregnant, or about living with his family, or other things, almost nonstop, even when i ask her not to. She doesn't understand that she's complaining about things that I want more than anything, or she doesn't care, since I told her that the things she's ranting about are things that I wish for and want badly. Besides all of the other things I'm dealing with in my life, this is one of the most depressing. I find myself moping or wanting to cry a lot of times.

This is mostly a rant but I'm also asking: Am I a bad person for being jealous? Any tips on how to stop being so jealous?

( Please don't tell me to leave them as this is not an option. If you don't like poly relationships please don't comment. I'm looking for advice and answers to my rant, not negativity.)