It's time to do a little soul searching and merciless editing.
Go back to your notes and your exercises. Arrange everything chronologically, and read your work from the time that you started your writing exercises. Read your work carefully and note the following:
1) Your writing strengths. Do you write using a wide variety of words? Do your conversations sound real? Are your characters almost literally jumping off the page?
2) Your writing weaknesses. Is your vocabulary limited to the point of your work sounding repetitive? Are your conversations stilted? Do your characters feel two-dimensional or even one-dimensional?
3) Improvements in your writing: are your sentences becoming more simple, lucid, and readable? Is your grammar getting better? Are your characters and stories feeling more real?
4) And, the reverse: is there anything that you haven't improved on or gotten worse at?
Take note of all of these. You need to know what you need to work on, and you also need to have encouragment in the form of the good things that you already have and also worked to achieve.
Keep this list and be a better writer on a daily basis.
Good luck!