You should have applied under the CEC(Canadian Experience Class) - graduate stream after 1 year of full-time skilled work experience - why didn't you? Anyway, if it's not been over a year since you left your job(the one under the post-grad work permit), then you can still apply under this stream.
From the checklist, you need an "eligibility verification" to apply for an off-campus work permit, which I assume you get from the designated school official - how would you get this when you have finished your studies? Your study permit is valid till Dec 2013 which means you can stay legally till then, so it is important that you only submit applications for which you are clearly eligible.
You have a few options:
1. LMO - you have to find an employer who is willing to apply for it and show that they tried and were unable to find a Canadian to do the job. It's not easy but it's possible and you can't know unless you try. Depending where you live, it could take months or weeks to get the LMO and then you can apply for a closed work permit. Plus, after working for 1 year in a skilled job, you will be eligible to apply under the CEC(graduate stream).
2. PNP - not very familiar with this stream but you should look into it for all provinces. Some have shorter wait times or less stringent requirements than others.
3. marriage - if you have a genuine relationship and your sponsor is approved, then it's worth considering. Note that there is talk of sponsored spouses having conditional pr status for a period of time but it has not yet become law. See: http://www.cic.gc.ca/english/department/media/releases/2012/2012-03-09.asp