Small olive plant in a pot

[sasquatch]

Novice gardener here, I have an olive about 18" high 2 years old.
It has small creamy flowers this year. I would like to put it in a bigger container, but what should I pot it with?
I think originally I used general purpose compost, some stones and my poor garden soil. and placed it by a south facing wall. Its growing, but should I be using something else?

Also, how do I get that Olive shape of the long stem with a bush of leaves on top?
my plant has a lot of leafy shoots all along the stem.

Many thanks.

A good quality multipurpose compost like John Innes 3 is recommended for Olives.

I'd think to get the shape you would have to remove the side shoots lower down.

sorry that should be 'A good quality multipurpose compost mixed 50:50 with John Innes 3'