Hi there! Some suggestions for help...
First of all, there's an Adoption Angels project here on WikiTree, so you'll probably want to get into contact with them.
Second, you'll benefit greatly from putting your DNA on GEDMatch. It's free to use, and lets you compare your DNA for free to people from other companies if they've also uploaded their DNA.
Third, there is an app online called Chromosome Painting, though there is also an app called Genome Mate Pro - both are free - that let you "paint" your chromosomes so you can see which part you inherit from which part of your family.
Fourth, getting your family tree up on a site (such as WikiTree!) can help you even more as you can keep track (for free with WikiTree) of your confirmed ancestors on your mother's side, and you can refer back to your tree and others' trees if you want to see if they might be related to you through your mother's side or father's side.
Fifth and lastly, if your uncle in question is your maternal uncle, then he would help to be tested more than your son. The reason is that while your uncle will have none of your father's DNA, his DNA can further help you figure out who is related to you on your mother's side. If they don't match him, but they match you, there is a good chance that they are related to you through your father's side.
Best of luck, it's a long journey.