Just keep in mind supplements aren't illegal and are commercially packaged and as long as you're not bringing in like a bulk shipment or something you have absolutely nothing to worry about. 3 trips in the last year for me and the most recent a few months ago and my supplements always come with me.
I take TONS of various supplements into or out of Thailand with me every time with 0 questions or 0 scrutiny and have been doing so for years. Same with medicines, well what little I take.
Go talk to 1 of the many visa agents and explain your situation and see if 1 of them can help you. I don't know how but these services often times can get things done better than the people who work at the immigration offices.