Difficulty conceiving a second child?

Just hoping to connect or hear stories about people who have struggled to conceive their 2nd child when they didn’t need help with the first? It took us 8 months to conceive my first and it’s been now 1.5 years of trying for our second. I have an appt booked to get some tests done but I don’t have anyone I can talk to about it that would understand. My best friend had her second baby and I’m overjoyed for her but there’s a part of me that feels sad/jealous which I know is awful but I’m still happy and excited for her! It’s a weird feeling.