"misty, if 11.00a.m. is in the morning, surely 12.00 a.m. is the next hour - therefore 12.00 a.m. is noon. Don't see how you can logically go from 11.00 a.m. to 12.00 p.m.."
I think you need to understand the way we have timed our 12 hours clock.
"a.m. and p.m." are Latin phrases which mean before/after midday. My understanding is they have been in use in English since the 17th century.
As a practice, we have made 12 o'clock the middle of the day. So, 11.59 is am, and 12.00 is p.m.
If you do some research, you will find that that has been the common way we call the time. If you don't believe that, try making an appointment with Tony Abbott to meet at 12 mid day, using your 12 a.m., you will be promptly corrected. I am sure of that.
