You need to work on why you got negative feedback and low stars.
The one from December. Did you ask for additional shipping than what was stated in the listing? You're not allowed to do that.
Can you use Paypal shipping labels in Canada? If so, you may want to use them. You can print the label without showing the amount of shipping you paid which may help your shipping stars.
The feedback you left for the two buyers who left negs makes no sense. Feedback is not mandatory so you should not have left any for those two.
Non paying buyers deserve unpaid item strikes.