Folks, I'm looking for advice on food size.

Our snake is now around 230g. 10%-15% of our snake's weight = 23g-35g. I buy f/t mice from local Petsmart/Petco, but we now seem to be in an in-between size from what they offer. Their adult mice are 20g and their small rats are 40g. That's a big jump!

I'm about to feed it a 20g mouse, but that's getting too small. What should I do instead? Should I try feeding 2 medium mice? They're around 14g-18g.

I notice that buying in bulk online offers a lot of different sizes, but we have only our one little BP, so I'm hesitant to buy 25 of one size as he'll outgrow it before going through it all.