I just got a new chair a few weeks ago, and luckily the armrests go up and down quite a bit, so I should be able to lower them to accommodate a table. It's the rest of my room that is small!

I have a cockatiel cage in the room, along with an air filter/purifier to keep the dust down he produces so that takes up a bit of space. I am thinking something like this:

https://www.amazon.com/Lifetime-80251-Adjustable-Folding-Personal/dp/B0074HYWFG/ref=sr_1_8?ie=UTF8&qid=1510765575&sr=8-8&keywords=folding+tray+table

Should do the trick well enough.