Tuala

I can't help with funding or US schools questions, but my thoughts would be: 
Working on your GRE scores from those baseline scores would be high effort with low payoff, so I would skip that option. Three schools is not that many to apply to, especially in clinical. I would apply to more next year. Having a publication on your CV will help next year, as will your summer grant. So those will make you more competitive without you having to do anything different than what you've already planned. Is your psychology GPA good? Is your SOP targeted enough to each school? Does it talk about your research and clinical experience in terms of your responsibilities and how they make you an excellent candidate for this school in particular? Overall, I think the single biggest thing I would do is try to get at least one change in who is writing your recommendations, starting with the person you think is writing you the weakest letter.

I think what helped me most this year was having full-time research experience - working as a research coordinator/data manager/research assistant can be very valuable. I struggled to find a full-time position at first so I took a temporary part-time one, which I think helped me get the full-time position. Email POIs you're interested in working with and ask if they have research positions available. Sometimes labs don't post their full-time positions online, so it's good to email the professors directly.
Other than that, your GPA/GRE scores are fine. Definitely apply to more schools. I don't know how the schools in Canada work, but if you are to apply to US schools, make sure they are funded programs. Most schools will tell you on the website. Also, look at the other forum topic about funding packages - you can see what those schools offer and go from there. 
I met people at interviews that had applied to upwards of 19 schools - that's incredibly high and very expensive, but they had multiple offers and were able to choose what was best for them. 

To be honest, from what I've been hearing from a bunch of my mentors, the process for getting into clinical programs in Canada is random and department politics play a huge role in who they can accept for a cycle (see: the discussion on Ryerson in the Canadian applicants thread). The only thing I would focus on is getting more publications and possibly finding better reference letters (although just because they're hard on you doesn't mean that they didn't write good letters). Applying to more schools, including those in the US, should help as well, especially if your research interests are more broad. Your GPA and GRE scores are competitive so I wouldn't worry about those. 

I was rejected from 3 Clinical programs in Canada I don't know what to do now.
 
I have two honours undergraduate degrees, one in Arts and one in Psychology and my cumulative gpa is 3.94. For GRE I got 165 on Verbal, 160 on Quant and 5 on Writing and 86 on the Psych subject exam, scores which I thought were mildly competitive. I have one paper that I am presenting in April and will be published soon and 2 years of research experience and many years of experience with the population I wish to study. I had a good interview with one school and I visited the PI before applying at another and she seemed really positive but then I just get a bunch of rejection letters. I think my SOP was really good, I had 10+ people read it. My big fear is my references might not have been stellar as my research supervisors have always been really hard on me.
 
I have a summer NSERC grant and I am trying to get a research job for the year but if that doesn't work, what should I do? If it does work, what else can I do to increase my chances? I will do anything and everything, should I retake the exams, do more courses to boost my gpa etc??
 
Also, should I apply to schools in the US? I am totally confused because there are so many and I have no idea how funding works. Any help would be appreciated!