I do not wear in public as frequently as I used to, but used to do it all the time while at school- college about 8 hours a day -but my schedule changed and do not have enough time now.
I just wear my relatively loose-fitting jeans and a 2XL T-shirt, which is long enough to hide the waistline at all times and no bulge. A pair or regular tighty whities keeps everything in place and is added measure against visible waistline.
I pee in them whenever I need to, but I never flood them. I learned to just do little bursts at a time. ( Basically you just relax, do not push or strain, let it flow naturally. As soon as the immediate urge dissipates, stop the flow. Just keep doing this whenever you start to feel the urge.) I would sometimes mess, but I would avoid being around people and only when I could change very soon afterwards.
I found the best course of action when you inevitably have to change in a public restroom with other people around, is to just walk straight in, take care of business, dispose of them in a sanitary manner, wash your hands and leave. Never hesitate and don't dawdle. If anyone notices, you want to act as naturally as possible and give them no reason or opportunity to say anything. Also, never pretend to use the toilet to avoid revealing the fact you are/were wearing a diaper, it only makes you more suspicious.
As for the few that will notice, most will have the common sense to keep their mouth shut. A friend, classmate, or coworker may say something, but most likely out of curiosity or concern. A simple, "I don't want to talk about it", usually suffices, but have a temporary medical reason on standy- bladder stone, UTI, etc. For strangers, just say it is none of their business and ask them to leave you alone- it really isn't no matter why you are wearing. If family or close friends find out. . .well that is another discussion. . .just tell them you will talk later and read the other threads about such cases.
Always carry some supplies- wipes, creams/lotions, spare diapers - and a change of clothes with you, leaks happen, so it is best to be prepared. If a leak does happen, just get to a bathroom and change. Do not make a scene by trying to pretend it is something else, just go without saying a word.