Oatbucket, the maneuvers used to stop SVT will not make it worse. Every cardiologist, doctor and EMT I've ever discussed my SVT with has recommended them and you can read about them online (search for Valsalva Maneuver or vagal nerve maneuvers).
Nobody will laugh at your questions. We were all new at this once ourselves.
Wow you sound just like me. I also started having attacks around age 13 but wasn't diagnosed til age 24. Kept being told I was having panic attacks, until someone finally bothered to check me on an EKG.
Anyway, anything that stimulates the vagus nerve can stop an episode and belching probably did just that. Another way of doing this is holding your breath and bearing down like you're going to the bathroom, plunging your face into ice cold water, gagging or coughing.