If you just empty your mind and head for the Void, that isn’t prayer yet. If you use Buddhist techniques in order to still the busy-ness of your mind, to free yourself from distraction in order that you might wait for God to give you the gift of His Presence, OTOH, that is Catholic. I don’t know that you had to go outside Church tradition to learn that, but it would be OK to try to still your mind entirely, as long as it is openness to God, and not mere stillness, that is the point of the spiritual exercise. If you don’t think there is a difference, you’re not on Catholic ground yet.
Contemplation is the highest form of prayer, it is certainly open to the laity, and it is no sin to desire it. We should desire it. Having said that, there is much to be said for using prayer time to recite vocal prayers, or to meditate on something in particular rather than nothing in particular, while waiting for God’s gift of contemplation. The “lower” forms of prayer are good and are part of what we should desire in our spiritual life, too. So it would be better not to make the “Buddhist” technique the only prayer you do. Praise, gratitude, and supplication are necessary parts of the spiritual life, too.
If you feel a need for alcohol or drugs to self-medicate yourself against stress or distraction, that is a problem. Try to bring your whole self into prayer, as you are, rather than getting into the habit of anethetizing the parts of your mind that you don’t have self-control over. God does not change those parts of you that you withhold from Him in prayer. If your soul lacks peace, bring the lack of peace to your prayer, which is to say to God, rather than trying to compensate for your shortcomings artificially.