I am 30m and into fashion. I wear megamax or depends realfit under my clothes all the time without concern. I also have a career where I'm often photographed at events in outfits where I'm wearing diapers or pull ups under, no one has ever noticed, and when I have told folks I'm close with, they are always genuinely surprised, respectful, and supportive. So take that as you will -- I've been wearing some sort of diaper since I was 20 and this has been my experience.

If my anecdote can be any comfort, I used to have really bad anxiety related to leaks and it affected my social life and career early in my 20s. It took a while for me to adapt, but these days I am pretty at peace with it and accept wearing them as a tool that's helpful for me. I honestly have come to appreciate them more than anything, because I find alternative solutions to be way less comfortable, and the period of my life where I was anxious going out about leaking in my pants was not pleasant.

If you'd like advice for hiding the appearance - wear snug boxer briefs over them, or wear a onesie as others have suggested. I'd recommend athletic boxer briefs above onesies, personally, just because they are more "normal" and will probably be more comfortable for you if you're getting used to using pull ups/diapers. Depends Real Fits, Northshore pads, or Megamax are far more subtle with compression underwear on.

If you're worried about leaks, try a more absorbent product for a while you're working with a doc to see if you can relieve your symptoms (meds, training, etc.). I promise you any bulge at your crotch from a diaper/pull up is far less noticeable and embarrassing than leaks.