“He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.”
1 Corinthians 14:4

He tells us:
“For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful.” 1 Corinthians 14:14
Prayer is communicating with God, when you speak in an unknown tongue, he says your spirit is praying- your spirit is communicating with God and he already told you what to expect:
“Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.” 1 Corinthians 2:12
Your spirit communicates with God’s spirit and he is the giver- he causes you to know the things that God freely gave you. In that communication, he tells you, your understanding will be unfruitful, you would not understand what you are saying, but be rest assured something is happening to your spirit- you are receiving enlightenment and you would become more aware of God’s abilities already granted you.
For the man who does not speak in tongues, he would miss out on all of these blessings- but that should not be you. There is so much God wants to show you, even now, so go ahead and speak in tongues more.