Does Low BB make Bunnyhops harder?

Hi, I ride a road frame with a very low bottom bracket. (245mm ground to centre with tyres)

Ive been riding it for nearly a year and have regularly practiced bunnyhops but they have alway remained very awkward and not higher than a couple inches. I can only seem to jump up straight, not front wheel first - back wheel after like I can do on other bikes.

I cant really bunnyhop at all when riding fast enough to actually hop something (would be a very tiny something due to height)

I feel for some reason I 'should' be able to bunny hop a lot higher. I have a friend who can bunny hop as high as he can on his BMX, on a track bike or lo-pro. Which is very very high. Most average people who can hop, I see them actually getting up kerbs etc no problem. But all these people are riding actual track frames with higher bottom brackets and I cant help but think it makes a difference.

Ive heard a lot of people say its harder to skid on a road frame, maybe its similar?

My frame is 56cm squared which I think fits well with risers but is too long when using drops. Would that make a difference? (I am 5'8")

My BB on my current frame is 4 cm higher than yours, but on my old frame it was around the same as yours, and I could hop just the same on it.
BB height makes a difference to how easy it is to get the front end up by changing your balance point at the rear of the bike. What it doesn't do is magically give you a good bunnyhop technique if you don't have it already, I think the best I can manage on a track bike is just a shade under 2 ft, but on 24 inch/bmx I can still get close to 3 ft (I used to be able to hop over 3ft on my bmx and smaller mtbs) despite not having ridden one regularly for over a year.
Its not about the bike its about the rider, sounds to me like you just need to practice with proper technique rather than continuing to try doing what you're doing, you need to relearn how to hop properly, check this out:

YouTube - Bmx amazing clip of 90cm bunnyhop very slow motion

Not perfect technique, but it gives you an idea, he should have travelled more upwards on take off as opposed to backwards (which just wastes energy) and upwards.

In BMX, trails frames tend to have a lower BB as it makes them more stable. Street bikes have a higher BB as it makes them more responsive and eisaer to hop.

In BMX, trails frames tend to have a lower BB as it makes them more stable. Street bikes have a higher BB as it makes them more responsive and eisaer to hop.

All true, my main point there was just that the difference in BB height is not gonna make you suddenly go from hopping a few inches to a few feet though.

A (slightly) higher bottom bracket may make it easier to bunnyhop, but I've found that it's also easier to bunnyhop on frames with a shorter wheelbase.

she's pretty hard already, imo

A (slightly) higher bottom bracket may make it easier to bunnyhop, but I've found that it's also easier to bunnyhop on frames with a shorter wheelbase.

That actually depends greatly on your physical size/body mechanics actually, some of the highest bunnyhops in the world have been done on a mountain bike no where near as short a wheelbase as a bmx, I for one can hop higher on 24/26 inch than on a bmx, I think because it allows me to stretch my body out more and get a better extension than the small cramped dimensions of a bmx
(despite bmxing for nearly 10 years!)