How can I add a wildcard text element to a nested IIF in text box form

Hi, this is probably simple for someone who does a lot of formulas. Here is my formulas that works great in my ms access 2007 text box.

=IIf([YrsofSvc]>=25,"25",IIf([YrsofSvc]>=15,"20",IIf([YrsofSvc]>=5,"15",IIf([YrsofSvc]>=1,"10",""))))

The [YrsofSvc] is returning a number so this is working fine. It is getting this number from another formula that returns the number + either Years or Months. So, some people return 2 Years, (or whatever), but others return "4 months"  Here's the formula for that, if it matters:
=IIf((DateDiff("m",[Date 1],Date()))>12,(Round(DateDiff("m",[Date 1],Date())/12)) & " " & "Years",(DateDiff("m",[Date 1],Date()) & " " & "months"))

So, what I am trying to do is get the first IIF statement to return "5" IF the 2nd statement is producing the word "months" . Some people have 7 years of service and that currently is resulting in a return of 15 days of vacation. However, for those that have 7 months only, NOT years, I want it to return a "5" (5 days of vacation).

So how do I get my if statement to evaluate whether it is showing months or years? I tried to do a wildcard in the IIF statement if it saw the text "months" but can't figure out how - not sure if that is right avenue.

Any help appreciated!
Diane