Hurray!

Today I had an English test. It was quite difficult but I've coped! I know that my English is not very good well, but now I have a certificate - upper-intermediate! Hurray! Sure, I'm not sure in my writing, but my talk in English was better than others had. Yeees!

Congratulations!!!!
Your sentence: Sure, I'm not sure.... is a little confusing. Probably best not to use the word "sure" twice. Maybe: Sure, I'm not confident in my writing...
And the second half - was it that you did a talk - as in a presentation speaking English - or was it just conversation.
If it was the first: my talk (or presentation) in English was better than the others'.
If it was the second: I spoke in English better than the others.
And, usually, at least for me, the stretched out yes is Yessssssss. (There's no rule on that!)