I like going to the gym too! (but I like swimming more).
It would be helpful if you uploaded photos to have a look (you can do so in the form), but from what you’ve described, it sounds like the classic gym-goer problem where you lift more/heavier weights that focus on “mirror muscles” – ie bench press to build your chest, much more than your back muscles.
It’s likely that this has resulted in a much more powerful chest than back, which has caused your shoulders to be pulled forward, causing the posture you described. At this point, you need to correct the imbalance by building up your back muscles – ie pull ups, upright rows, etc.
Obviously, this is only based on my hypothesis from what you’ve told me so far. There could be other reasons too, like poor habitual posture etc.
Personally, I would always advise patients/friends/family AGAINST going to a chiropractor. I’m a firm believer in scientific and evidence-based medicine, and they tend to practise treatments that have no evidence whatsoever.
The best professionals to help you would be a physiotherapist and Sport Medicine doctor.
Cheers
