Fishing static nymphs if you feel the pull it is quite often too late to hook up.
Focus on the line between the rod tip held not too far above the water and where the line enters the water.You will usually see the take here.From a high bank or similar point the rod at the water.If you are not retrieving the nymphs on the swing with some mends or changing rod position during the swing the line will normally lift when a fish takes the nymph.Not always but majority of the time.Some times the line will drop back so be ready.On the retrieve it will be more or less the same and try to see the take as opposed to feeling it.Ahhhhhhh Grasshopper..............You might well not be old enough for this one lol.
If conditions allow you can watch the tip of the fly line in the same way for any change in the natural movement which may signal a take.
I know easy to say and not so easy to do and we all miss takes due to the very nature of the method some we do not even see anyway.
Another tip which may help is to smoothly draw(not a snatch) the line with your reel hand as you lift into the fish.This will help eliminate any unwanted stretch factor.You should not need to do a Zorro to set the hook on a trout.Smooth tightening is the name of the game nymph fishing because if you feel nothing then leave the fly in the zone and it may well be taken again by his mother.
If conditions are pretty calm you could try using an indicator/bung which will help.
Keep at it and you will no doubt crack it and begin to gain more confidence and at one with your gear turning enquiries into solid hook sets.Not all the time I must add but maybe an improvement of the current ratio
Good hunting JP