Why is it so difficult for me to learn how to drive?

So, I’ve been learning how to drive and it’s been really hard for me. I understand what I need to do, but when it’s time for me to drive, I lock up. I’m assuming it’s jitters everyone gets when they first start driving. But, I feel this fear is holding me back from a lot. I’m learning in a Jeep and I know the alignment isn’t off, but I when I’m driving, I drive a little too far to the right and I feel like I might scrape other cars, but someone has to point it out to me. How come I’m not catching onto this? I need help measuring my distance. I’ve been to a driving class and my instructor said I did fine but I need to cut myself some slack.

Thank you all.