Schengen Visa Rules (Munich)

Hello people, I must say I am very confused by the Schangen Rules and I have found out about them only after my arrival in Munich.
I am a Canadian citizen therefore I know i have the right to stay for 90 days maximum without a visa.
My stay in the Schengen Zone will be of 93 days, after which I will go for 33 days to Romania (which is not part of this zone) and afterwards go back home to Canada.
The way I understand it, is that I am overstaying my Schengen Visa for 3 days (my visit in Romania does not affect my day count since it is not in the Schengen Zone).

This situation raises a few questions:
Did I properly understand the Schengen Rules?
Is my 3 day overstay very grave?
Does anyone have any experience with this?
Is there any form/visa I can apply for to extend these 90 days?

Thank you for your help people!
Cristian David