USPS integrates with Canada Post on our side (interesting enough so does Hongkong Post as well as a few more countries - they all integrate seamlessly with tracking and billing). CP won't be of much help, at least not until sufficient time has been given for your package/s to arrive. Standards for mid-tier services allow 7-10 business days. In your case it's been only 5-6 days. Because you're not using a broker, you're subject to all kinds of delays (Customs) being the biggest. The problem with USPS and Canada Post is that they don't have the 'sender' fill out all the paperwork - such as declaration forms, tariff forms, etc. There is a reason why you need to fill out pages and pages of forms when you ship with broker-based services such as FedEx and UPS. That paperwork expedites the process and saves them from trying to figure out what's in the package and how it should be tariffed, if at all.
Bottom line... ship USPS/CPS and you're going to be stuck waiting. Good news is you probably saved a lot on shipping.