Based on your STM32 files, using the piggy-back STM32 (mini) card is a poor method of deployment.
Since I can only see the pins you have available and used, I did two layouts in twenty minutes, which make use of the available pins in two different packages.
One layout is based on the LQFP32 (STM32F030) package (32 pins) and the second layout is based on the LQFP48 (STM32F103) package (48 pins).
I'm only missing the USB related part of the schematic so I didn't add it.
Since the number of lines you are using is low, there is no need to use a package with a higher pin count.
Since your STM32 files do not contain the schematic of your piggy-back (mini) board, I am unable to add the USB and other related components needed for USB communication.
The pins selected are based on their physical package location, the MCU can be rotated 45deg, 90deg, 135deg, 180deg etc...
Board dimensions are 100mm x 100mm (exactly), 3oz copper with continuous current support of 8A, 16A peak, 24A surge and since you limit the peak current at 10A the chances of popping a trace are slim.
If you think the traces wont support the listed currents then you don't understand the dynamics of stopped traces (or even what they are).
As a design thought, the IR2101 has two inputs (HI/LI) with non-inverting outputs (HO/LO), if you can find a substitute that gives you one non-inverting output (HO) and one inverting output (LO) you can reduce the drive lines from six to three because you can drive both HI/LI from the same line and allow you to switch to a P/N channel H-BRIDGE with minimal circuitry required for dynamic braking thus increasing performance.