I have same problem with TS. Just walk few metres or climb stairs, start sweating. Easy to sweat but cant stop unless shower. My BMI also normal. But my condition call hyperhidrosis. Nerve problem which make excessive sweat than normal person. For deodoran at armpit, i use nivea happy shaving. Smell nice, no foul smell. I think TS shold change under shirt to singlet maybe? Two tshirt make body hot n humid and easy to sweat and slow to dry and make the smell.

Also try use liquid detergent for wash your cloth. Usually powder base soap will make cloth stink. Maybe coz got soap residue? Or not dilute well myb?

Lastly try change your diet. Eating strong smell food like garlic, curry and etc also can make strong body odor. Can take but not everyday.

For me, yes use nivea happy shaving can solve my problem sweating at armpit. You can use spray type coz more dry not wet like roll on. You can try first but result may vary. Can get at guardian/watson but find at woman's shelf ya coz that for woman's deo haha. But men also can use.

You also can try diff fabric for your cloth. From my exp, cheap black tshirt fabric that can find common at uptown tend to smell bad when long time use. I dont know why myb coz the black color they use? I always wear jersey type or 100% cotton.

You can use powder detergent but try not leave any residue to your cloth ya..

Hahahaha i like that nivea happy shave smell. I dont know but nivea for men smell not so good for my taste. I used nivea for men dry one, but smell stink when evening. Oh good point using happy shave, after shave your armpit, can use this deo straight away. No sharp pain woo. Also whitening purpose haha.Nahhh smell so lembut, only you can smell it, other people cant smell it. You can try buy small one for testing purpose.