Breathing Freestyle

Hi Everyone, I have a serious breathing problem when swimming freestyle. Either I hold my breath - which I know is a very bad habit for several reason or I try to blow it out - which is the way to swim I know. The problem is, that whenever I breath out under water I either end up having some air left in the lungs, or run out of air while still doing strokes and eventually when I get to the stroke where I planned to come up for air I gasp for air and have water going down my throat. Because of these I don't have time for breathing in properly. In the same time water goes up in my nose if I blow out all the air from my lungs uinder water- which I read the way to go (to blow all the water while under) in order to only breath in when breaking the surface for air. I often end up with lots of air in my stomach which makes me belch... In addition I have a low endurance. I can do only 1 or 2 laps at a time... I have a personal coach but it's not so much he can do from outside of the pool. I noticed that I cannot swim smooth, effortlessly - which is one of my goals in the long run, beside being able to swim long distances in all strokes. I always end up swimming relatively fast, when I should be going slow and focusing on my technic. Should I slow WAY down somehow? Any advice/drill is welcommed.