First Time PCB Design
As a recently graduated High School student, I shall formally welcome you to the club!
I have a few notes:


Your Vias are too small. The internal plating can be quite thin, and the current capacity is generally defined by the hole size, not the annular ring size. Rule of thumb is to have the internal hole diameter roughly the hole width.
If you specify no soldermask over the two large traces, you'll be able to flood them with solder, which should give you enough bus current capacity.
Your status indicator LEDs are overlapping
Large SMD resistors aren't really any harder to solder than PTH.


And, I just realized the extent of the chat discussion precluding an answer, this might be duplicate.