Conditional format for overdue date

Hello,

I have tried to firgure this out by reading other threads but cannot seem to find a formula to apply to my spreadsheet. Long story short, I am trying to create a spreadsheet to determine if a medical or dental appointment for a child is over due. Essential I would like the overdue date to be highlighted in red.

So for example, I have the "last medical date" in column "I". Each child is supposed to have a medical every year. In column "L" I have put a formula that inputs the date exactly a year from the "last medical date". I need for the date in column "L" to be highlighted if it is past a year from the date in column "I". I guess it would be helpful too, if I can create another condition that changes the color for dates at 9 months??????

Oh, I am using Excel 2010....

Please help!