Most plants will usually outgrow their pots. I think bay is actually a tree, so keeping it confined in a pot might not help it much. About all you can do is to see if its root bound once you take it from its current pot. This is usually seen if the roots are a solid mass under the soil surface and you have problems trying to get it out of the pot.

Recently I bought some creeping phlox and was having a major problem trying to get it to come out of its round pot. It turned out it was so badly root bound that it even closed up the drain holes in the bottom. I had to crack open the plastic pot just to get it out. I was hoping to also seperate the several plant stems, but because the root mass was so solid I had to use a knife and cut through the root mass, which is not a good way to get plants to grow. In any case, you could try trimming roots, but even for that, they will eventually grow more, and after a few trims the plant may not grow well.

If it's doing well, it might be better to leave well enough alone. I tried to re-pot one and the one I kept died on me.

Another piece I gave away did survive, though.

It sounds like yours is used to the size pot you have provided for it.