Finished 6 months coumadin (warfarin).Us was clear. Wearing comp stockings still daily. Should I take aspirin to prevent another dvt? What dose if so?

Congratulations. Likely Aspirin is useful. 325 mg daily. Depends on cause of DVT and has that been eliminated? Obesity, activity, surgery, cancer etc.
DVT. If your ultrasound is ok then you can stop coumadin (warfarin).Aspirin does not help in dvt.If you get this problem again then you would need work up for hypercoaguable state.