Weird because the 44,5 just fits good.
This is not at all unusual. It is VERY common for people to be riding boots that are 2-3 sizes off of their measured (actual) foot length. There are a lot of things that can affect this, but the two most common are:
-The boot is actually produced smaller/larger than the manufacturer's stated size.
-The rider has a boot that is actually too large/small for them (almost always too large).
I am in no way saying that your boot is too large, but just for reference this is the standard we use:
Your boots should be snug!
The most common complaint about boots is that they are too loose, not to tight. The junction between rider and board begins with the boot, as it is in the most direct contact with the rider. When fitting boots, use the following method: A. Slip into the boot. B. Kick your heel back against the ground several times to drive it back into the boot's heel pocket. C. Lace the boot tightly, as though you were going to ride. NOTE: This is where most sizing mistakes are made. A snowboard boot is shaped like an upside down "7". The back has a good degree of forward lean. Thus, when you drop into the boot, your heel may be resting up to an inch away from the back of the boot, and your toes may be jammed into the front of the boot. Until the boot is tightly laced, you will not know if it is a proper fit. D. Your toes should now have firm pressure against the front of the boot. As this is the crux of sizing, let's discuss firm pressure: When you flex your knee forward hard, the pressure should lighten, or cease, as your toes pull back. At no time should you feel numbness or lose circulation. Your toes will be in contact with the end of the boot, unlike in a properly fit street or athletic shoe (snowboard boots are designed to fit more snugly than your other shoes). When you have achieved this combination of firm pressure and no circulation loss, you have found the correct size!
Let's dial this part in and then we will all be able to help you with bindings and board size.