I notice that your post has been up for a while, I'm not sure if you've already received your response...
As of right now, PTAs are not officially licensed in Canada. Most new PTAs are the products of training programs, but numerous older ones are trained on the job. There is a relatively recent initiative by the Canadian Physiotherapy Association to have a support worker (ie PTA) assembly that may lead the push for licensing one day. The biggest factor for you would be to find employment, if jobs are available I'd imagine that your chances would be good as a trained PTA with experience.