Could someone tell me about tritypes?

Hello,

I am an INFP 4w5 sp/sx, I don't really understand tritypes but I tried to learn a little.

So after months of researching and analyzing... I have come to the final conclusion:

Heart type: 4w5

Head type: 5w4

Gut type: 8w9

Can someone help me figure out my tritype, I don't really understand how the stacking works, like how do we find whether it is say for eg: 548 or 584 or 458 etc?