I have 200 hours in a 150 and I'm your height. You'll get used to it. Keep in mind that the 150/2 is a better training plane than the 172. It will teach you to respect the rudder and the crosswinds, while a 172 is forgiving to the point that it may become dangerous. Also, anxiety is normal initially. I'm saying that because there's a difference of ... 1/4" between the two planes' cabin width (39 1/2 to 39 1/4).