Incomplete formula for if

Hello everyone.

There is wrong with my formula. Here is the context

If the AP.Internal is "billed" equals to recheck the monitoring

But

If the AP.Internal is "unbilled" equals to recheck the monitoring

This condition is same with AP.RAW MATERIALS, AP.Overhead,AP.INVESTOR that if it's billed equals to for managers approval but if not recheck the monitoring

But for AP.Supplies, AP.third party, AP.Fees, OT external audit regardless of the status. It should return as "do sanity check"

My formula was:

If(and(c2="ap.internal",d2="billed"),"for managers approval","recheck the monitoring"),if(and(c2="AP.Supplies, AP.third party, AP.Fees, OT external audit"),"do sanity check","")

Before coming up with the formula. I tried to use it works

If(and(c2="ap.internal",d2="billed"),"for managers approval","recheck the monitoring")

There is something wrong with my formula. I'm not sure if the if formula is most suitable or should be xlookup?

Thank you for helping me. But kindly explain to me how can I like understand how do you come up with the correct one. I'm trying to learn be independent working on formulas.