There's a gap between what I think I am capable of doing and what I am actually able to do, and I've noticed that this happens more often now.
こんにちは!
ご質問ありがとうございます。
ご質問について、いくつか言い方が考えられますが、例えば、
There's a gap between what I think I am capable of doing and what I am actually able to do, and I've noticed that this happens more often now.
とすると、「想定と現実に乖離がある。その[頻度](https://eikaiwa.dmm.com/uknow/questions/120330/)が増えたことに気づく。」を表現できます。
参考になれば幸いです。