Welcome to the forum. Given your background, I think it would be wise to explore your potential with natural supplements before jumping into PH's or anything more serious. If you've only used a multi and protein, there are a lot of great natural products available that can help you gain an edge and make progress.
First off, what are you goals? Is your main focus fat loss or muscle gain?
Before knowing too much about your goals, the first supplement I would suggest as a staple in your stack would be creatine. Whether bulking or cutting, creatine can provide you with a great foundation to help with strength and muscle gain. I'd recommend a product like CreMax XT, which includes a full serving of creatine, 2.5g of betaine, glycerol, and an electrolyte blend that can serve as a great supplement foundation for any goal.
Beyond the basics, if you give us some more info we'd be happy to help you out and figure out what would be the best stack to get you to your goals. Best of luck and welcome to AM