Hello Hannah, I am just a few months ahead of you.
Related to creating another Master (for Bold), this might be useful (its answer after mine) if you have not got this far.
I cannot remember all the details of how I did this but this is a link to the user guide:
And this might be useful:
I see in my Font Info this:
Masters
You see both are listing.
Not sure what Metrics are showing in yours, they are the lines you see when editing.
They are the same in my Regular and Bold.
See the Weight number, the Bold, I made it a larger number.
Exports
(I have not yet finished the font, so not sure if all my settings work on actual export, but I have been using Window menu > Text Preview to check how it looks, although I sometimes use the free Font Goggles.)
In Glyphs, you use cmd-1 and cmd-2 to swap between Regular and Bold.
There is some kind of script you can use to populate all your Regular Glyphs into the Bold cells, if you ask here, someone will give you instructions, but I did it by copy/paste just one-by-one as I made each bold.
Make it Bold
Have you tried the Filter (menu) > Offset curve?
I found if you add a different number in the Horizontal then click in the Vertical, the horizontal will update, so you can play around with the numbers clicking between them and see if it works for you.
Otherwise you could select (by dragging) an area of points and then drag them in the direction to make it bold.
If you have too many points there is Filter > Clean up lines and Filter > Delete short segments which might work (I did not have much success with them and ended up deleting quite a few unneeded points to make it easier to expand to the bold I wanted, but I have had experience with vector paths previously.)
Variations
I was not going to add any variations using scripts, but now I have my Regular and Bold done, I have started playing around with these possibilities. Ask at the forum here for help if you want to go into that area, it’s fun. For example some or all of your letters at either the beginning of any word or at its end, can be a variation of how they “normally” look, and letters that occur together, perhaps like ss or fi could be what is called a ligature where as you type in those two letters one after the other and they then look slightly different as a pair, perhaps joined as you might do if you are using a pen on paper.
Additions
You will probably want to add things like numbers, question mark, ? ! + - / { } arrows, etc.
Right-click on the Punctuation or Symbol options to add them to your Glyphs, then add them in, you might have some already.
And I think you add a space, which defines the width of a space when you type spacebar to separate words.
Someone here might comment back about what I have typed here for you if it is incorrect or could do with clarification or extra links.
Have fun!