TTC seeing a doctor or persisting?

Hi IMs
I am currently 23 and TTC my second child with my partner. we have been TTC for about 8 months and I do have regular periods and when my son was conceived it was the first cycle without protection. I guess what I am trying to ask is when should you consider start seeing someone in regard to "difficulty" conceiving ? I know I am young and we haven't been struggling for years unlike some couples and I already have a beautiful son who I am so fortunate for. I am not trying to sound like my issue is bigger than anyone elses as I am aware some people struggle for years but for piece of mind I would like to rule the possibility of being infertile out. I want to also mention that I have Crohn's disease and I am unsure if that will effect me TTC. Wouldwait longer or would see a doctor? Do I see a GP or a specialist? Any direction or advice would be much appreciated.