In terms of the US, you're pretty much fucked. Why didn't you get a pardon???
Now the US has you on their system and they will never take you off, even if you get a pardon (they say they don't recognize pardons). Even if you get wiped off the Canadian system, the US has now downloaded it into their system where it will stay forever. You're now red flagged and can expect to be stopped every time you try and enter. Be aware, it's a criminal offense NOT to declare your criminal record when entering the US. The first time you were able to say you didn't know but now they have it on their system that you've been caught and next time they won't be so lenient. Now they will say you're trying to "sneak" into the US without declaring your criminal record.
You should apply for a Canadian pardon and then apply for a US waiver. At least you can say to the US that you've obtained a Canadian pardon (which means you've been "clean" for, IIRC, the past 5 years).
You're likely going to have a tough time with the US because you have an assault conviction. You could be denied a waiver based on that. Without a waiver you are ineligible for entry into the US. They will likely flat out deny you entry. The waiver is the process by which you get an exemption from the bar. People with criminal records are automatically barred from entry to the US unless you have a waiver. If you keep "sneaking" in, you'll get caught and they may give you a permanent ban (i.e., no waivers for you).
The best advice I can give you is to go speak with an immigration lawyer PRONTO. You'll get better info and a path forward from them.
