Hi there, and welcome to the board!
I would suggest trying firecalc, which you can reach by clicking on the link at the top of this page, or by going to
A very simple approach that would probably be accurate enough for your purposes now (since you're probably 10 to 15 years away from retirement anyhow) is to:
a. Figure out what your annual expenses will be when you're 48. A good guess is what you're spending now increased by inflation for every year between now and then.
b. Figure out what that teacher's pension will be worth when you're 48. Probably take your current salary, increase by your average expected wage between now and then, and then multiply by that 45%.
c. Subtract (b) from (a).
d. Multiply (c) by 25. This is the amount your retirement savings needs to be at 48. Note that you'll need to not include the kids' college $ and not your home equity unless you are willing to do a reverse mortgage or something.