If it feels light and you believe this is the problem, then you need to saturate the entire medium, so run a couple gallons of water through the pot slowly and make sure everything gets wet. Hopefully that helps, then after you water make sure they have ample time to dry back. A good way to avoid this in the future is always saturate the medium completely from the start and add an ample amount of perlite to the soil, at least 20%. The perlite helps with allowing oxygen to get to the root zone in between irrigations.
Don't get discouraged if they don't make it, if you learn from it then you can always do better next time bro, good luck!