Legal to sell in the UK, but not in the USA. How does the location of my website play in to this?

I have a company in the UK which sells a product that is "Legal" here in the UK.

But its considered a medical device in the USA and do my understanding it cannot be sold "Within" the USA...

To my understanding I can ship the product to the USA, I have done so for years and my partner has done so for over a decade I believe this to be because the "sale" of the item is illegal in the USA unless you're a licensed doctor, however it's not illegal to own or posses the item.

The customer is buying from my UK Company, they money is being received by a UK Bank/Merchant Processor etc...

Currently the website is hosted, on a UK Server, but I'd like to switch to a USA Server since %95 of my customers are in the USA, so I want to speed it all up...

I'm trying to understand if I could be breaking some laws, if the website is "Hosted" in the USA, does this mean the "Sale" is taking place within the USA?