Sounds to me as though the grip is either too thick to hold properly or its radius is too far back and you are struggling to reach the trigger with your index finger.
Conversely the hand of the stock might even be too slim, in which case it could be worth wearing a glove to help you get more of a grip.
If the hand is too thick then a gunsmith can soon slim things down sufficiently without weakening the stock but if the grip is pulling your palm and fingers too far back you might have to consider changing guns.
Before taking such a drastic step, why not talk things through with a gunsmith to see what can be done and also ask to try friends’ guns when you’re shooting together at the gun club?
If you find one that suits, check yours alongside it to see where things differ.
That said, have you stopped to consider that there might be nothing wrong with the gun… and that the problem is actually being caused because you are holding the gun incorrectly?
You shouldn’t hold the gun so tightly that all your arm muscles tense up, but neither should it be too light.