Chipes of Vocabulary

Whenever I learn languages such as English, French, and Japanese, I feel that vocabulary is very important. I already had this problem many times to learn English. At that time, I had to follow it up, so I memorized bunch of vocabularies. When I was a freshman, I took a Japanese class for  fun. However, it was not so easy because it’s so different from English or French. English and French have quite many similar words  which makes me confused, but it was too difficult for me to learn chinese characters and imagine pigeon from word ‘hatto’ easily. That’s why I temporaly gave up learning Japanese. Now I got this emergency problem specially in learning French. I feel that I always use same expressions and easy sentences, I can’t express my opinion very well in discussion or presentation without my dictionary. Unless I study vocabulries by myself in my free time, I can’t get many words even in classes. I have to try to learn new words and expressions. However, I feel that I don’t have a teenager’s brain anymore. My brain is dying?? Recently, I can’t remember and memorize vocabularies as well as I was a teenager.  I hope it just I’m learning two languages in the same time and I’m too busy to spend many times studying vocaburies. I want magical chipes of vocabulary. I know that if I passed this huge step, I can improve my second languages, but this step is quite long and I get stressed a lot.  Have you guys had these kinds of problems before?