Your inseam and PBH numbers are suspect. You need to measure your PBH properly.

Just looking at the pictures it does not look too small for you. Your seat is not set all that high.

If you feel that you need to stretch out a bit more, just get a longer stem.

It doesn't sound like you have too much standover.

In fact, depending on who you listen to, you might not have enough. If you only have an index fingers width standover on a 52, say a centimeter, you won't have any standover on a 54.

Standover on the 54 is just shy of an Inch taller than the 52. And that's with the stock tires. You might find yourself in contact with the top tube on the 52, if you should decide to fit larger rubber as it is.

You are not a candidate for a 54cm LHT IMO.

You should be looking at either the 50 or 52.

You seem kind of long in the upper body so you might be best off with the 52cm and leaving it there.