Are you seeing any discharge? A white, cottage-cheese looking discharge accompanies a yeast infection. If you see that, I'd say you defintely have a yeast infection!
Vagasil is only an anti-itching cream, and won't help the actual infection. Get Monistat 7 Day Treatment. I used to get yeast infections all the time, and I never had a problem with the 7 Day treatment. On the other hand, the 1 and 3 day Treatments were horrible, and my doctor forbid me from ever getting those. The 1 and 3 Day Treatments have such a concentration of medicine in them, they can severely irritate the vagina and worsen your condition. Even when you are on your period, you can take Monistat (I did, anyways).
Grab come Monistat, and use the Vagasil whenever it itches. If the yeast infection persists after that, go see the doc. They'll just give a pill that they pretty much only dispense when all other options have been tried.
Good luck!