Need help with dimensioning

Hi, so I'm practicing for the CSWP. I'm currently working on a segment 2 sample exam, and for the last problem, it's asking to change the angle of part of the extrude. However, when I try changing the angles, it makes the end much smaller than it's suppose to be based on what's supposed to look like at the end.

I'm not sure how else to approach it, so any advice on what can I do to make the angles not shrink the end so much would be great.

My answer:

https://preview.redd.it/yjyg6r1qm55e1.jpg?width=640&format=pjpg&auto=webp&s=9a2ddb32c45a3c72c9909923a0acdb9fa50e78ad

Correct answer:

https://preview.redd.it/ocyhynzrm55e1.jpg?width=864&format=pjpg&auto=webp&s=53aef50062234b91ffd02b4f38b2de64574f2978

Here are the files, if you'd like to take a better look:

Shell_Q11.zip