No test can rule something out 100%, there is always a margin of lack of accuracy or error.
MRA is a sufficient screening tool for your clinical history though. Your symptoms do not suggest basiular insufficiency but further testing for this disoder might include a trancranial doppler ultrasound of the posterior circulation.
Basilar insufficiency tends to cause symptoms like drop attacks, loss of vision, eye movement abnormalities, side-alternating weakness, clumsiness of the hands and feet among other symptoms.
Injection angiograms are more detailed than an MRA but are you willing to risk a 0.5-1% risk of stroke from the angiogram for a 0.01% chance of finding an abnoramlity. All these things need to be weighed up when we are talking about screening for abnormalities with tests etc. The pre-test probability to findings something based on teh history and exam is the most important factor in choosing a test and whether is it useful and worth it or not.
Your condition sounds (informally) like chronic daily/intractable headache, and may benefit from seeing a headache specialist and perhaps some joint injections or botox.
I would encourage you all to read this thread. Myself and others have written extensively about this phenominon.