Hi there, I'm not an accountant but I can share with you my experience. As I have turned primary residence into rentals and then back. You should always have an assessment done when you change your property from primary to income and back an forth. This is a stake in the ground for CRA to calculate your capital gains during the time it was an income property. Like you indicated you didn't get an assessment, so I would contact MPAC (if you reside in ontario) and have them provide you your assessments for the years you need. CRA should allow the MPAC assessment as the appraisal. In this case it may work to your advantage as MPAC assessments are generally lower than Fair Market Value.
www.mpac.ca