The first thing that is really evident, is that you have not left large enough gaps between the Mains AC and the secondary of the transformer.
Here are three documents that can give you more insight.
IPC2221A: Generic Standard on Printed Board Design.
UL61010-1: Electrical Equipment for Laboratory Use. (if you have access to it. Other "sources" might be available)
UL60950-1: Safety of Information Technology Equipment
These documents are a lot to read and understand, so as a general rule, you should keep 2mm gap between traces/pads on the mains side, and 8mm gap between the mains and the low voltage, where you might touch with your hands the conductors.
You can go below these clearances, but you need to know what you are doing, and this is where the three documents listed above, come into place.
As yours is a hobby project, and space is not a big issue, stick to the values I have given you above, or greater, and you will know to be safe, as long as you stay below the 300VAC.