Jealousy

I am almost 20. Married to the most amazing guy! We just bought a house both work our asses off for everything we have and want to have in our future! I am not able to be on birth control because my body can't handle it! Okay. My sister who is 24 lives with a dope head of a boyfriend! Just let us know that they have been trying to get pregnant and are now pregnant!! May I add that neither of them work! They live off of food stamps and get checks! (We weren't raised that way, but hey people go their own ways all the time!) well anyway we aren't trying to get pregnant but even though we aren't I can't help to get jealous because we can afford a baby! We are married have a stable house had jobs everything!!! And yet she is the one who is pregnant! I haven't talked to anyone about this but I need to vent and talk to someone about this! Is this selfish of me or is it okay to feel like this? I just don't understand why it's so easy for people who can't afford to take care of babies or don't want kids to get pregnant but it's so hard for people who really want baby!? I'm just so jealous of her😒😒