Hey Sheila, this will be the hardest chord to get right in the G chord family. Just keep at the muscle memory practice, going real slow, and moving your finger out of the way with your right hand if you have to. The muscles in your finger will learn to get to the new position on their own after a while, but they need time.
You can also try to play the Am7 without your pinky down, just with your 1st and 2nd finger. Some people prefer to play it this way. It will just make transitioning out of the Am7 a bit more difficult. So you pick your battles.
You never fail until you quit!