I am a 33 year old very social female and I comfortably wear suits, dresses, shorts, shirts - everything. I generally use the wraps from ostomy secrets or spanx. No need to cut a hole in your shirt, but at the same time, do what feels most comfortable for you.
I tuck the pouch into the wrap or spanx above my underwear and underneath my pants. I generally pull my pants up to the belly button area to fully cover the bag. This can be a little tricky for tighter pants like jeans where the top of the jeans may move half way down the pouch when I sit down. If I remain in a position like that too long, there's a risk of part of the bag's adhesive getting unstuck from the skin.
Also, for me, I generally have to empty the bag every 5 to 6 hours. It starts to get noticeable if I'm wearing a tight dress at around the 5 hour mark. I empty it a little more often when I'm wearing a tight dress or suit. The suit jacket definitely helps.
I agree that dresses are the best for hiding the pouch
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