How to deal with people close to you getting pregnant?

I haven't been ttc that long compared to others, only 7 months. But it is getting hard to not be jealous when other people are pregnant and I'm not.

I have 4 SILS that are pregnant. And my baby sister called me in tears a few days ago saying she took a test and it's positive. She is 18, she's not ready for a baby (her words) and doesn't want one right now. Why did God give her a baby when she is not financially, physically, or emotionally ready for one? Yet I am ready and want one so badly, but I haven't gotten pregnant yet.

I have not said any of this to her and won't, I'm being supportive and listening to her fears. But I'm frustrated and sad and feeling like it's just not fair. I just needed to vent my feelings.