Hi Code! Based on what I can see, it looks as if this armor is a bit too large for your frame and will more than likely need some adjustments. Not all troopers are the same build of course, but as stated in the CRL for Basic approval: Requirements for all 501st costumes are proportional to the wearer in scale, fit and size.
In photo 1, it appears that your posterior plate is sitting pretty far away from your... well... posterior. I realize that you (as I do) have a slender frame, but the armor should be more "form fitting" as seen in the reference images.
This photo surprises me the most. A general rule of thumb is that you should just be able to slide your hand in between the top of the thigh armor and your leg (give or take a bit), and it looks as if the circumference is way too large.
The shoulder bells are riding kinda' high and sitting out pretty far away from the chest plate, and I believe this is due to the strapping. Without a picture I can't be sure, but I'm thinking that the bell strap is glued too far down below the top edge (yellow arrow) causing it to ride up. Gluing it all the way to the top should eliminate both issues. This will also help to hide the tops of the biceps, but those could (should) be raised as well. Note in the reference image how far they sit under the bell.
We are here to help every step of the way with any specific adjustments you need to do, Code, so not to worry! Will it take some work on your part? Yep, but we are here to guide you and make sure you end up with a spectacular set of armor! I would concentrate on one area at a time, and posting up some photos wearing the complete set before you start would help immensely. Let's do this!