Olive trees

Hello all.
I have two olive trees. There are in pots - any advice on the size of the pots please. Do we think they are big enough or no?

 

I'd say that pot is big enough, but the plant looks a little starved.
Maybe some feeding would help.
A close up pic would be good.

 

Pot looks fine infact better than the ones mine are stuck in. As said above, a good feed maybe.

Mine are in too small pots in knackered clay soil and looked dreadful. Plunge watered/fed and now lush and full if flowers. Been nipping the growing tips too.