Matthew, Firstly I do not know any PRO who does not tell a pupil they should be lower , Do not jump to change the shaft , Your not preforming in competition could be more a mental issue ,trying to concentrate for 18 holes is to long , Try to break down the round to say SIX HOLES AT A TIME , ( This advice was given to me by a senior pro who was still on the tour at the time ) and it worked for me I was 19HC and dropped to 14 very quickly and got lower .Don't think about your next shot or club until you reach your ball .then make a decision and follow it through first instincts are normally the best . I don't believe your Pro did not tell you not to up the club head speed as it only can lead to over swing and loss of control in the back swing better to keep control and just accelerate through the ball, If your clubs are not custom fitted them perhaps they should be ,also be careful if you go for a fitting try not to get excited as the adrenalin flow will increase club speed which also happens when playing in competition and where shots get lost and balls . Practice makes PERMANENT not perfect, followed by consistency playing within yourself if you can't be sure to reach in two then don't try but place the ball to a distance you know you can put the ball close to the flag . GOOD LUCK