This will be my second cycle so I haven't been trying long
If you reschedule, you might have this same issue every month (if you don’t conceive) unless they can time it carefully for after your period and before ovulation. I’d probably do the check now because fast forward 6 months, if you’re not pregnant and then find out there was an issue it will feel like wasted time. Difficult to know what is the “right” thing as you need a crystal ball. Good luck!
How long have you been trying? If it’s quite a while, I would do health check so you can get some answers either way. If it’s not long then can you reschedule?