First I circled the two grounds. The traces are too small but maybe OK. The two grounds are connected by a very small trace! OUCH. There is resistance and inductance in this small trace!
In the second picture I showed how I would make the ground stronger. This is the minimum I would use. I use more ground area than I showed.
Then you change sides on a PCB, the VIA has resistance and inductance. If the current is large I use many VIAs on the same trace. You are using a 0.01 ohm resistor and you have traces with large current that have more resistance than the resistor.
Look at examples of other power supplies. There are examples using your IC. Use examples form Linear Tech. Do not use examples from some strange person on the internet. I included a picture of a PCB from TI. Note the large grounds. Vin is large, Vout is large. At these high speeds through hole parts are not used much. Their legs are too long to work right. Keep high current traces short.