Paul's comment about ADHD seems like really good advice, but assuming there is no medical solution to your dilemma, maybe some words of encouragement may help:

When you first start off programming professionally it feels like there's an infinite list of things you should have already learned, and it can be really overwhelming.

I remember my first job out of college, it was really stressful at first. Good news is that after a year on the job you'll feel like you've done it your whole life. There will always be things to learn but it slows down drastically after the first few months.

One bit of advice I have (and not everyone will agree with this) is that if you really feel that you're falling behind your peers, you may want to work longer hours than they do. It'll give you more time to learn and people have a lot more patience with someone who shows they're trying.