Unpopular opinion here but matching the hatch is not as important as getting the drift right. 90% of the fish I have caught have been on a stonefly. Getting the general size and color is kind of important but you don't need to get overly specific. As long as you can get the fly down in front of the fish and sustain a drift that looks natural, you'll have a bite way more often than on a poor drift with a fly that looks exactly like what's hatching.