I just want to talk about myself
I studied English for 8 years, but I can't remember that so many words. <em>(Note "that much / that many": "I don't have that many friends." "He doesn't have that much time; he needs at least two hours to finish that project.")</em>
It's difficult for me to remember these words now. I don't need to study English in school, but I want to study for myself because I think it's very useful and I like making friends with people all around the world. (Apart from capitalizing the "I", these two sentences are perfect!)
<em>(You've retained a lot of English. Excellent work!!)</em>