Time Card Hour Calculations only for Reg time, Overtime & Doubletime with Lunch Break

I think I have finally figured out how to get the calculations done for my time sheet into 3 categories, Regular Hours, OT Hours & Double Time Hours.
I'm running into a problem with the OT hours. I need it to show only a Maximum of 4 hours the remainder go into Double Time.

here is how my sheet looks with in/out times
TimeSheetPic.PNG

Here are my formulas for each:
Reg Time
=IFERROR(IF((((C15-B15)+(E15-D15))*24)>8,8,((C15-B15)+(E15-D15))*24), "")
OT ( I need this to max out at 4 hours)
=IFERROR(IF((((C15-B15)+(E15-D15))*24)>8,((C15-B15)+(E15-D15))*24-8,0), "")
Double Time
=IFERROR(IF((((C15-B15)+(E15-D15))*24)>12,((C15-B15)+(E15-D15))*24-12,0), "")

Any help is appreciated!

OT column is only calculating 2 hours and 0 Hours for DT when the final out time is 11p or 10p when using that formula.

If it matters the cells for in/out are set to number w/2decimal places since there can be quarter hour uses.