My point is that it is not a major "Mistake" compared to your grammar.
But hey , at least you know some English , you can take English classes if you want , it doesn't hurt ;D
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Well, that's true since in Serbia when we say "I" It is not capitalized therefore it is unusual to me to capitalize it. But yet again, a lot of people don't do it and it's not a big grammar mistake.
I have heard by some people that in some schools it is not mentioned nor corrected if students write it like a normal "i" :/