I don't look like anyone in my family and I have always had this feeling that my family has been keeping things from me.
I also have areas of my life that don't make sense. I'm 34 and these questions have been weighing heavy on my heart lately.
I would welcome any suggestions on where to go from here.

I have 5 boys, they don't look alike, you may look like someone from 4 generatoins ago, or a combination of several. Looks mean nothing.
What did your parents say, have you asked them? Have you asked a aunt or other relation.

And the funny thing is, I have a son who is adopted, everyone who does not know he is adopted tells me he looks more like me than any of my natural children.

I have to agree with Chuck here. My ex had 3 sisters, not one of the 4 of them looked alike or like their parents.

My current husband is adopted and so are 2 of his siblings. It is hard to tell them from their adopted parents. My husband and his sister look alike, but she was adopted from Germany and he was adopted from Russia. My father in law gets compliments frequently on how he looks like his oldest son... his oldest son was adopted in Texas.

So, it now comes down to asking your family whether you were adopted.