When you speak "in tongues" can anyone interpret what you are "saying"? Do you speak a language you don't know to people who are getting saved by your speaking in their language? Otherwise, I don't believe you. My daughter and some of her friends were in a pentecostal church (which I admonished here against---she finally had enough discernment to come out of it. They attended a 6-month class and before they could "graduate", had to "speak in tongues". I asked her to explain it to me. She said that she and her friends all faked "tongues" so they could "graduate." The pastor of her church did an obvious faking of it, also, in front of the congregation.
At Pentecost, the disciples who spoke in tongues were talking to people from many different dialects, or tongues, and the people who were hearing their language, which the disciples had not previously spoken, were able to hear their message.
I can understand the Holy Spirit using Christians to convey messages in languages that they have not previously used, when the Spirit wants to draw people, but most of the "tongues" noise is a lot of nonsense. You've determined the origin is from God.... but didn't explain how you would determine such a thing. Did anyone get saved as a result of your speaking gibberish?