I am almost fluent in English, howeverbut I'd like to keep improving and become a more natural speaker. I am almost fluent in English, but I'd like to keep improving and become a more natural speaker.

Your original use of the word "however" is definitely accurate, but since you note that you want to speak more naturally I changed it to "but", which sounds more like everyday english.

I haven't practivced French for a while, so I don't feel very confident about it. I haven't practiced French for a while, so I don't feel very confident about it.

I haven't practived French for a while, so I don't feel very confident aboutwith it. I haven't practived French for a while, so I don't feel very confident with it.

I'd like to start adincluding it toin my daily life again, maybe by watching videos and improving my listening, since I don't have the means to take classes right now. I'd like to start including it in my daily life again, maybe by watching videos and improving my listening, since I don't have the means to take classes right now.

I think this would sound more natural.