I once had a Spanish teacher, who also had problems remembering what that kind of time specification stands for and I came up with maybe a trick to remember. We do the same thing in German, so I guess it translates:
Lets say you have 11:00. That's easy. But what about 11:15? We would say "quarter 12", so I guess the English version is "quarter of 12". How to memorize, that this is 11:15? Well, you can imagine a round clock and the minute pointer has moved _quarter of its way to 12_. So you only have a quarter of that hour "already done". 10:30? We say "half 11". So I guess English is "half of 11", meaning that the minute pointer has moved half the way to 11.
Maybe this will help.
(Actually I personally usually don't use those ways of specifying the time, neither in English nor in German. I just say the 24h format as it is written: "11:15" is "eleven fifteen", 13:35 is "thirteen thirtee five" not 1pm something.)