A bad memory

I used not to like learning English, but now I love it. 
About ten years ago, I worked with a young woman who could speak English. At that time I was very bad at English. On the other hand she could discuss with foreign companies in English. How cool she was! I was very impressed and it triggered me to learn English. 
Now I enjoy learning English every day, but even so I think that I wish I had learned more during my school days. That’s because it's shockingly hard for me to remember new words. 
For example, if I tried to study three new words in turn, I forget the first one in only one minute. Such as ‘mundane’, ‘platitudinous’, ‘tolerance’. To master these words, I needed to repeat sessions more than ten times. 
Or if I tried to remember three new words those starts from character ‘A’, I was confused their meanings. Such as ‘adverse’, ‘abrupt’, ‘avert’. Even if I could remember them at that time, I would forget after a couple of days. 
And idioms? I give up! 
However my vocabulary is steadily increasing little by little. So I can continue to learn English while having great fun.