I am not sure where to start. I came to Canada as an immigrant at the age of 22, I had studied English a little. I passed the Toffel in less than a year for the university admission. I think my score was for the listening, reading 470.
Although I have studied two undergraduate degerees and worked in a telecom company as a programmer. To me, my English sucks big time! I sometimes go blank, don't know how to find the right words together. Especially, when I have to explain something technical.
As a new comer, I had more vocabulary and grammer knowledge compared to the the time that I have lived here. I got a lot of admiration and vow for my English level as a new comer. However, I don't get that kind of reactions now!
How can I improve after all these years, there is not enough time for me to study English. I have a lot of techincal material to study, however, when I want to emphasize on learning the sentence structures I fall behind in my reading. I can only read to understand the concept and be able to verbalize it in a few words or sentences.
Depressed and disappointed
From reading your post, I think you may be judging yourself a little harshly. When you've reached a high level, it often seems that you're not making any progress because it's much harder to measure and see. It's easy when you're at a lower level- you don't know, say the past tense, and then you learn it. ASt higher levels, iot's more about fine-tuning and that's harder to measure or see.