Happy but angry

So my bf and I have been ttc for almost a year now and haven’t been having any luck. I track my ovulation days and everything. My cousin (who has only been off birth control for about 2 months) just texted me telling she’s unexpectedly pregnant. I am so happy for her but part of me is so upset and angry and sad. I’ve been TRYING for a year and she JUST got off birth control and gets pregnant. I was at work when she told me and had to go sit in my car and cry. I feel terrible for being so angry but I just can’t help it