Only way I could help was for you to learn to fish!
Like I said ... balancing act .... but think you are gaining on the db side of things.
Don't forget to check into config of Apache ... might be able to reduce apache presence/footprint memory wise that then could be used for DB. Also learn about 'top' and how to use it on a Mac server. While not ideal, your small site might do well enough when/if using SWAP space for DB - that's something server will do ... not really anything for you to tweak.
Am sure 'shingled' DB admins would shutter at that last statement, but when one has only what one has .... got to work with what ya got!
'spirit of sharing', Ken