The simple answer is that you (probably) can not do what you've described.
Under the US Visa Waiver Program, if you go from the US to Canada and then return to the US, then the time you spent in Canada is counted against your allowed stay in the US. In your case, your initial 65 days in the US, 14+ days in Canada and then 21 days in the US would put you over the allowed 90 days.
At this point you basically have 3 options...
- Plan to leave North America before your 90 days is up. As you're already in the US, you can check the date by which you need to leave, either by checking the stamp on your passport, or going to https://i94.cbp.dhs.gov/I94/#/recent-search
- Keep your current plans, but on re-entry to the US from Canada ask the immigration officials to issue you with a new I-94W, giving you an additional 90 days of level status in the US. Whilst the immigration staff do have the ability to do this, there's no guarantee that they will. And if they don't, then they will potentially refuse your re-entry to the US based on the fact that you don't have a flight to a location outside of North America within your allowed stay.
- Re-order or re-time your trip, such as that you are outside of the US on the day your status ends.
To explain the last point - if you are outside of the US when your I-94W expires (even if only in Canada), and then you attempt to re-enter the US then the immigration staff will need to issue you with a new I-94W, giving you additional time in the US. Whether they will do this will depend on the situation. For example, if you are just returning to the US to catch a flight home in a day or two, then they will likely allow you into the country. If you are returning to the US with plans to stay an additional 30/60/90 days, then there's a real chance they will refuse your entry and leave you stuck in Canada.
Realistically, simply shortening your trip to be less than 90 days (Option 1 above) total is the best and safest option. Whilst Option 2 will allow you to do what you want, there's a very real chance that the US Immigration staff will not allow it.