Should I go back to my coach, or can I shoot my way out of trouble?
Some people can overcome shooting problems through a well thought-out regime of practice, but it sounds to me as though you’re not sufficiently experienced to shoot yourself out of this particular hole.
As such I recommend you go back to your coach and find out why you’re missing certain birds when shooting.
From one or two other things you say in your email you are not exactly on top of your technique and this is something that needs to be addressed.
Practice is only of any real use when you have a thorough understanding of how you shoot, and why you miss.
Firing a lot of cartridges at the problem just now will only compound your difficulties because you will simply end up practicing all the wrong things.