Liam, I'm assuming your pretty young & of a smaller physique than your average player ?.
So your choices are
1. You hit the gym or maybe start some intensive calisthenics, very good for improving muscle strength without bulk.
Or
2. You sell your m4 & get something better suited, shorter, lighter & better balanced, personally i'd recommend a plastic bodied bullpup, Aug/PDR-C/UAR/TAR-21/FN2000 etc, or maybe a p90, any of those would be a big improvement on what your using now.