Back stroke trouble for a newbie.

Hi, My post is bit descriptive as I am a newbie. As I mentioned in my previous post, I just started learning swimming at the age of 35. By mistake I took 5 classes on continuous days and bailed out in the last class of embarrassment that I couldn't do what my instructor taught new.swimmingforums.com/.../sad.gif new.swimmingforums.com/.../sad.gif But, I just found later in a day when I went to practise that I am able to backfloat, then started moving my arms, I started moving and started using my legs also. After 3-4 days of practice I am able to Backstroke (both arms synchrnoized), able to finish my laps comfortably with the same style. Now I am trying to add the conventional backstroke (using alternative arms), I am finding it difficult. I am not able to move in a straight line and water gets into my nose.. legs also sink .. Is it normal when you are starting this stroke, but I see it improves for 3-4 meters again goes bad, again works for 2 more meters again bad... Feeling bit down whether it is not for me. My idea is to swim the way I comfortable and then train for front crawl ( I love leisure *** stroke)...