A slightly different take on this from someone who has been through fertility treatment- twice! (And no IVF needed either time- just some help with ovulating)
your post doesn’t really make it clear if you are wanting to try for a baby or not.
If you go to the GP they will ask you this. Might be worth a conversation with your partner first.
If you consider you are trying for a baby, and have been doing so for 3 years with no luck, at your age it would be worth getting the initial testing for sure.
If it’s more just curiosity as you’re not too bothered at this stage but would be in future, a GP is unlikely to order any tests for you- they are done as part and parcel of a fertility referral usually.
a lot to think about and I remember both times thinking “oh shit, this is real, we actually do want a baby and I need to sort it now”. I knew in my early 20s that we would have issues as I’ve PCOS (diagnosed due to other symptoms which I had investigated as they were debilitating) and I’ve also got endometriosis which causes pain etc. But the GP wouldn’t refer for fertility tests as we weren’t trying for a baby then.
GPs in particular will ask you what you want from the appointment when you’re there. If it’s a fertility referral and initial tests then say so. If it’s wanting to have information incase it’s an issue in future, but no referral, they might not order the tests as a lot can change over the years and these tests cost the nhs money (and can add to the already huge waiting list for fertility treatment)
Ovulation predictor kits aren’t too expensive if you wanted to check whether you ovulate (if you’ve regular periods and no hormonal contraception then most likely you are, but worth checking!)
I hope that helps and you get the answers you’re needing- knowledge of any condition is a good thing I think! Try not to be scared