"If you have to look closely to see the difference, there isn't enough contrast."

Do this now

Convert your design to black and white. If the hierarchy disappears, the contrast was being carried by colour alone. Fix it in black and white first, then add colour back.

Unpack

Contrast creates meaning by creating difference — in size, weight, colour, space, or tone. Subtle differences register as mistakes, not decisions. The black and white test is the fastest way to find out whether your design is actually working or just looks like it is.

Draw it.

Fast and messy is better than perfect.