Really struggling with keyboard layout in #Linux

Ideally, I´d want to press:
' + o

To get:
ó <=(want this)

But then if I press:
I + ' + m

I get:
Iḿ <=(dont want this!)

Instead of:
I'm

In Windows, the US International Keyboard layout does this. In Linux, I've tried more than a dozen English and Spanish layout and none seem to work this way. Testing layouts is a chore because there can´t be more than 4 layouts active at the same time.