This is a classic case of how the PRTB is useless for landlords. You have a determination order, but what is it worth. Tenant can still stay on, you cannot evict her, for this you need a court order, who is going to pay to to go court, who is going to pay you for lost rent, your order states it is the tenant, who is going to enforce that.
If you evict her illegally for sure you will be paying. And tenant knows that and is probably waiting for you to make a mistake.
If the tenant does not leave on the correct date I recommend you contact the PRTB by email and letter and see what they will do. Would be very interested to know their response. You could be lucky and the tenant will leave. You have my sympathies.
There is an organisation for landlords called the IPOA who you can contact for advice.
Could you outline to us how long you have been without rent? And what amount is the rent.