Seems like a fairly sensible plan. Use the .45 to fall back to gain the shotgun or the AR. A couple of queries come to mind, however;
1. Why "put down" the .45 to get the shotgun? Presuming you're not wearing sweats or elastic waistband pants, why not retain possession of the short gun while the 12-bore is used?
2. With your solid-wood doors, if you think a 12 gauge with buckshot won't penetrate it from 12 feet, why do you assume a .223 bullet will penentrate
3. Flashlight - Xeon bulbed preferred. Where is yours? Unless you live alone and a neat housekeeper things can move around, especially cell phones, shoes, slippers, etc. And you can use the bright beam to momentarily blind someone in near darkness.
4. Others in the house? What are your plans to move them to your safest room?
5. Presuming you barricade in your bedroom (1st floor or 2nd?) but the BG(s) don't bother you except to prowl the rest of the house. Your cell phone call results in rapid PD response. How do you let the cops in (presuming the BG didn't crash the front door)?
A) I read a great idea somewhere - make a simple sketch map of the interior of the house. Roll up and insert into a plastic tube with "House Map" showing. Connect this to a key ring with a spare house key(s) and one of those $1.25 chemical light sticks. When cops are arriving, activate light stick and tell 911 operator the color and what window you'll toss it out of. This allows cops to find map & keys easily and to ID the "good guy" in his room.
B) Go to a discount store like Ross/Marshalls/etc and buy a long cheap scarf in a bright or light color. Tie this to the key ring instead of the lightstick.
C) Tell the cops to wait outside with body bags and a carpet shampoo machine.
6) Most importantly, what to do if the point of entry is from outside into your bedroom "safe room"?