Glad you've sorted it, Lauren. You might also consider a hobby mitre box to give you even more control. If it is too deep for your saw, just put a strip of wood on the bottom.
https://www.amazon.co.uk/s/?ie=UTF8&...l_21pc2u0m70_b

It is also good for starting a groove for right angles and boxes, followed by a scorer and/or files. Dennis.