You should keep all your documents, doc's notes, MRI reports, everything in a file organized & on hand. Take it with you when you seek an opinion from a new, different pratice. It is best you keep pushing. Sometimes doctors get too busy to look for the actual problem. I take all signs seriously when it comes to the brain/head! If you try a few different you will atleast rule out things & that may make your worry easier! Good luck to you!
It's always good to get a second opinion, especially when it comes to health issues involving the brain (and such an important gland, to boot!).
That said, your doctor is probably right with taking the wait-and-see approach. They probably weighed the benefits and harms of surgically removing it, and you'd be hard-pressed to find a doctor who will immediately recommend removal of a pituitary tumor that small. I'm interested to hear why they didn't put you on medication to shrink the tumor and help with your headaches and other symptoms, though. Did they mention medication at all? I would also push your doctor to have another MRI done in 6 months, rather than waiting a full year.
Good luck, and keep us posted!