I was always confident in my English when I was a secondary school student. However, I am now very frustrated when it comes to writing English essay. I don't know why, but grammatical mistakes seems (this should be "seem" not "seems".) to be unavoidable. The worst? I didn't notice them even after I proofread.

This is so frustrating...
I wonder if there are any grammatical mistakes in the above. ( Delete the phrase "in the", so it would be "I wonder if there are any grammatical mistakes above.") If there aren't any, I will be glad to know.