Unfortunately, it's never a good idea to do any premature celebrating when on probation. Probation has the authority to call probationers in for random tests, and you appear to be aware that your case is not finally over until August. You are not the first person to get caught out by a last minute random test.
Unfortunately, too, so long as probation files the violation against you before the August date your case is supposed to be over, you can face sanctions, even at this point on probation. You don't get jail credit for time spent at liberty on probation. So you need to call your lawyer, because when you're violated, you will want someone to make an argument for some sanction other than revocation and a resentencing to jail time.
What you have going for you if you test positive is that you were not rearrested, and this is just a technical violation. What's going against you is how late it is in your probation as well as the fact that you've been in trouble with a positive U/A before.
In my experience, under these circumstances, your probation is likely to be extended and you'd be monitored more closely. But jail is possible, so if you're violated make sure you're represented at the hearing.