Adam Smith looks nice on paper but in fact not even England and the United States became the economic powerhouse they came to be via his policies. In fact they became industrial powerhouses through strong protectionism. It was Alex Hamilton's Report on Manufactures, not Adam Smith, that guides US economic policy in the early republic. It was the protectionist policies of Henry Carey that guided US economic growth in the post-civil war era.
Similarly, it was English protectionism that led to the rise of the textile industry, and replaced Belgian cloth for English, and the Navigation Acts (copied from the Hanseatic merchants) which led to English commercial supremacy. Not free trade.
"one assumption you made that i disagree with is that trade instantly means that industry leaves your nation which isn't necessarily true."
No, it doesn't necessarily leave, but in order to keep it from leaving you have to make a conscious effort to specialize in it, like for example Germany has. Notice how Germany is one of the few industrialized countries which isn't being de-industrialized. This is because it specializes in making high-end manufactured goods for export and created a technical education system geared for this specialty. But few rich countries have done this and instead specialized in providing financial services, like the US & UK, because that is where they had a 'comparative advantage'.
"when many people spend a lot of money on a good people will begin to supply more of that good such that they meet the demand."
The power to produce wealth is more important than wealth itself. For example, Germany has suffered many a century from war, famine, pestilence, etc, but it has been able to rebound very quickly after each calamnity. Why? Because it maintained its power of production. Ditto France in the early 19th century, suffered a great deal after losing the Napoleonic wars. Yet rapidly grew due to its powers of production.
"you can only market goods to your own people. this means that you are disadvantaged when compared to nations who can produce for the entire world"
Disadvantaged when it comes to one particular kind of market/good, but on the other hand you have the advantage of having many more types of markets & goods produced. The strength of the national economy is the total amount of goods & services produced, so it doesn't follow that just because markets to the goods & services you specialize in might not be maximized, you won't have an overall greater level of productive capacity.
When a country specializes, it is making a choice between either sacrificing labor intensive production in favor of capital intensive production, which means greater structural unemployment; or sacrificing greater capital intensive production for labor intensive production; which means a less advanced level of production, less technical know-how, and a lower standard of living. This is why despite the fact that African economies have been plugged into the global 'free trade' system for decades, they can't raise the foreign exchange necessary to industrialize or create a manufacturing sector. They have to export at a very high level to get the kind of foreign exchange necessary for industrialization, and that just isn't possible since there are too many competitors.