请英文达人帮我纠正这篇我自己写的文章里文法和句型,

If you could change your life, what would you want to do?
And if you could achieve this goal, how would your life change?
根据你的下文,建议修改为
If you could change your life, what would you want to do most? And how would your life be changed?
I wouldn't want to go back into the past
(mainly because I wouldn't want to relive that again)
but I could change anything I would be my lack of confidence.
这里为什么要用would呢,难道你现在愿意回到过去吗?建议改为
I don’t want to go through my past again, because I don’t want to relive the life of lacking confidence, but I could change everything if I can build up confidence.
II didn't have any confidence in myself.
For example, When I read passages or answer questions in class, I am so nervous that I can't say a full sentence.
不知道你想表达的是不是现在有信心,而那时没有.姑且这样理解,建议改为
In the past, I didn't have any confidence in myself.
When I read passages or answer questions in class, I was so nervous that I could express myself in a complete sentence!
After class, I speak fluently, but whenever teachers call me, I feel afraid.
The reason why I failed was that I lacked confidence.
这里时态不对,建议改为
However, after class, I spoke fluently, but whenever teachers called me, I felt scared. I always pin the blame onto lacking confidence.
So I think that's what I would change.
I want to be full of confidence any time.
建议改为
So I suppose that's what I have to change.
I want to be full of confidence all the time.
My life would be perfect if I had full of confidence.
语法错误,建议改为
My life would be perfect if I were full of confidence.
I think, maybe I can go to a great college.
There can be no achievement without diligence and self-confidence.
Of course, I like Soochow University now.
这几句不知道你想表达的与前面有什么联系,建议改为
There would be no achievement without diligence and self-confidence. If I can regain my confidence, I will go to a great college, Soochow University, my favorite.