At times, learning a language can become oppressive. Rules, regulations, exceptions, word order, pronunciation all add up to make the big picture look too big. Things we thought we had already learned are forgotten, and it all becomes a blur at the very moment we need to communicate the most.
One of the consolations to this problem that I can give is that the satisfaction of being able to communicate your message as best as you can is a goal worth achieving. Building a language is similar to raising a child. A language is a living creature that continues to grow. You never know what your child will become when he or she grows up so you just help him to do the best he can day by day. Imagine the big picture while increasing your vocabulary. Look at the mountain of words that you have already learned and compare it to those few words that you knew when you started e.g. Hello, Good bye and chocolate! If you look at it from bottom up, your oppression will turn to aspiration. Then when the day comes where you have to show off what you know, you can do it with a smile!
Give yourself a pat on the back and congratulate your achievements and you will get back on track, one word at a time!