Question: My probationary period passed three days ago, I have not been told if I passed it, and I have my evaluation early next week. Should I assume that I have passed probation?

Answer: 
Never make any assumptions. Talk to your manager, mention that the period ended, and ask if you need to fill out any paperwork, or if there is an official review involved.
You should wait until any official confirmation.

I had a similar situation 4 months back, the confirmation meeting was delayed because of too much work.
Since you know your meeting is next week, you should wait until then.
In the meantime, you can take feedback from other colleagues about your performance to ease the pressure.