You just have to choose how you want to play, if you want to be competitive with top arena players you most likely will have to put money into it. But if you are willing to grind daily and be in the middle of Arena pack then staying F2P is very doable. I went through the same slump as you around the level even all the way to 70 with the whole energy lacking and SIM tickets lack. But that was do to all the low cost gear farming I did at that time. Burn through my sim tickets every day and had to wait and wait just to save enough energy to even battle a mission.