Anything smaller than 10mm is classified as a Microadenoma and so is pretty small really. Yours sounds about the same size as mine was although when it came to surgery I think the surgeon said mine was fragmented so it was a little tough to get it all out. I'm seeing him next week for a follow up appointment so will see what he says. The following week I'm seeing my Endo for blood work etc
I had surgery in September and so far things are looking good. Things were clear in the MRI, my blood tests are looking normal, my blood pressure's down, I've lost weight, my ankles aren't swollen and I've lost the hump and moonface. Touching wood I can say that I'm getting my life back. There isn't a part of me that Cushing's didn't effect but thankfully it's all looking a bit better now.
Recovering physically from surgery and the adenoma isn't the tough bit. It's the recovering from Cushing's and the devastation that the Cortisol causes that's the tricky bit.
Larger tumours are easier to spot on MRIs and can cause problems like putting pressure on your optic nerve which makes you lose peripheral vision but I believe surgeons have a better chance of getting everything out without leaving any damage.
Good luck with everything !