Need advice

So my husband and always planned to try to get pregnant after my sister got married because I didn't want to be pregnant at her wedding and I figured that could be my last hurrah. My sister had the same plan to try ro get pregnant once she was married as well. I was of course was excited, I wanted to take this journey with her so our babies could grow up close in age together. It took me 2 cycles to get pregnant. Now 6 months later my sister is still not pregnant. As far as we know she is young and healthy with no issues likes PCOS or endometriosis. Regular cycles. I try to be as supportive as possible for her and I'm sure she is excited for me but I feel as the months go by that I'm pregant and she's not she holds some resentment towards me. Sometimes its hard to talk to her about being pregnant because I don't want to make her upset but at the same time she's my best friend and she's the person I want to send belly pics and ultrasounds to but I don't want to do it if it hurts her feelings. Has anyone been in a similar situation and have any advice? Thanks.