Echoing everything that's been said here re: equalizing first at 15' is far too late. Also that trying to do so while free diving is different than while on a regulator, so don't sweat it if it's been an issue to date.
My instructor had a very good technique to first learn equalization (and I'm certain yours will as well...) so to share...
Assuming you're in a pool where there's a slope from shallow to deep, position yourself on the floor of the pool right at the top of the slope, feet down towards the deep end. Slowly...SLOWLY...hand walk yourself down the slope, equalizing every "step" or two you take with your hands. Once at the bottom of the deep end, retreat back up to the top and do it again, changing technique if there were any issues (to use the descriptive language, from 'block the nose and gently blow against' to 'block nose and swallow'). Worked like a charm and neither my wife or I had any problems equalizing once we moved over to vertical decents later.