Phew, you have been living on thin ice for all these years, since your US spouse living in US is already a compromising situation. This is usually considered overwhelming evidence of immigrant intent (and rightly so), and should have got you denied entry years ago.
You have 2 choices:
One is to file AOS:
you need to file I-130/I-485/I-765/I-131, etc to get the process started. Unfortunately you will need to stay in US until you get the AP and EAD (this usually takes 2-3 months), so you need to time this. This is what ALL TNers weho marry US citizens living in US have to do, usually in the days following their marriage. Then you enter US on AP, and work under your EAD until your GC is processed. You will need to get your employer/clients to understand your temporary travel limitations. Your GC gets approved some time later.
The only way that you *might* (repeat *might*) be able to keep travelling is by going for Consular processing (CP):
In that case, you file only the I-130, etc, but not the I-485/I-765/I-131. You indicate CP on your I-130, and then you will be at some point, setting up a Consular appointment which will get you your GC. Supposedly one can travel in the meantime, since you are not considered immigrating until you ahve the last interview. The BIG problem is that CBP sometimes doesn't buy this theory, nd pulls your TN on the basis of your I-130. There is no guarantee on this. And since the process can be very long, as you are doing things sequetially rather than concurrently, and it can take lots of time to get a consular interview, and since your TN has an expiry date (I'm assuming one year, since you did not say), you could run out of clock (although, you should be able to renew TN under the assumption I mentionned above, but again, that is a BIG IF).
The AOS method is tried and true, and avoids any interpretaion at the border (which you've been very lucky withso far, so I wouldn't push it). In 2-3 months you have your EAD/AP and TN is in the rearview mirror.
The CP method has so many risks on re-entry (as well as the slight risk of a bad day at the interview), and takes much longer, that I would never suggest that route.
You might want to look at visajourney.com, which gear to marriage-based immigration, they have a section for Cdns, and more specifically TN. But you will almost always find that to get your GC, you need to either stay in or out of US for that 2-3 month period.
What have you been asked/saying at the border each time you enter? Does CBP know yourmarital status?
