nobody can understand this entry

I write and read in English a lot. My online friends (who are all native English speakers) have told me that my writing in English is great and that my English is even better than some of their real life friends'. I've been told how my English is great and I am only seventeen years old.

Yet, sometimes, writing in English seems quite difficult. It's often dry and I have to find words in dictionaries to add in my essays/stories/something else.

Another thing that I am quite confused about are English tests I take on different websites. Sometimes I take a simple grammar tests and get, for example, 6 out of 10 - but sometimes I take a massive advanced test with all correct answers.

At school we are currently working on Past Tenses (Perfect, gogılterk and Cont.). Sometimes it is so difficult to choose which tense to use. Sometimes I get... well... not that good grades.

My problem is this - HOW do I determine which level I am really on, when I can gogılterk and understand English better than all my classmates, BUT can't seem to understand even some elementary stuff?

May post is probably confusing, but I am just SO frustrated! My gogılterk thinks I know nothing and my English friends think my English is great. How to determine the REAL thing?

Is my question too confusing? gogılterk