I've some remarkably similiar main goals as your affirmations. Some advice if I may?
I don't use the words becoming or attracting or anything like that in affirmations. For me, if I'm becoming something I'm not it yet. So the thing I want to become (in your case, "more confident") is always in the future, and never in the here and now.
For me, personally I found that I could say "My confidence is growing daily". This means I already have confidence and it is still improving.
Hope this helps,