Protein Deficiency

I've been a vegetarian for 6 years. It's one of the best decisions I've ever made. I have a problem with reocurring protein deficiencies. They manifest differently, so I'm always in the doctors office with different complaints. But the root is always the same. Protein deficiency. Anyway... My doctor wants me to resume eating meat.

I need to know where I can get additional sources of protein in my diet. I eat a lot of nuts and beans. Although not generally when the weather is warm. What else can I do? Are those protein shakes you can buy at GNC good for you? Is there a kind of a protein supplement? Is there something that can be added to my beverages like Metimucel? Something, Please!