Hi Jodiann and welcome to the forum. It's nice to hear you're having some success :)
Regarding a niche market, these type of markets are really only found one of tow ways. Either many hours of test marketing different products to gauge results over an extended period of time or to get extremely lucky and hit on a product by sheer chance. Because of this, anyone that has discovered a good working niche will rarely share it because sharing their effort then adds to the competition and that of course then destroys the niche they put their effort into finding to start with.
So I don't think anyone is going to give that information up easily, at least not if thy're smart. If I had a niche product myself, I would keep it well hidden or at least as well as possible.
Regarding FBA. I'm not an expert in the field, but I can't see the difference between using it from inside the US or outside really. Maybe I'm missing something, but FBA is a fulfillment service. So they warehouse and distribute your products, meaning you're pretty much hands off. Given the hands off nature of fulfillment services, I wouldn't think your personal location would be any issue at all.
If you have a good reliable relationship with your US suppliers, then that's the most important part of it right there.
Still, would be good to hear from anyone with personal experience in using FBA, either US based or international.