What happened is that when you were confirmed, you were not well disposed for Confirmation (meaning you had an incomplete understanding of what it was about and were not, in a sense, spiritually prepared for it and were not cooperative).
You received the Holy Spirit but it did not manifest itself. You received the gift, but did not open it. It lay there unopened and unused for years, until you were ready to appropriate it in a Life in the Spirit Seminar, now that you understood things and became properly disposed. You "opened" the gift you received at Confirmation and Baptism.
Consider how Paul instructed Timothy in 2 Timothy 1:6–7 (RSVCE, NKJV):
"For this reason I remind you to rekindle the gift of God that is within you through the laying on of my hands; for God did not give us a spirit of timidity but a spirit of power and love and self-control."
2 Timothy 1:6–7 (RSVCE, NKJV, NRSVCE)