No periods

Hello....
I was on the pill cerezatte for 4 years I came off on 8/12/14 to try for a baby and my periods have not returned. My periods stopped when I was on the pill. I'm 27 years old.
My doctors said I was under weight slightly, I'm talking a few pounds. I'm now a healthy weight for my height for a few months now....still no periods. 
I do have a small appetite could this be a problem do my portion sizes need to be bigger? 
Also does alcohol or caffeine affect periods? Should I just not drink at all (I probably share a bottle of wine/prosecco with hubby one night in the week then again at the weekend with a cheeky cocktail) 
I also enjoy the gym 3/4 times a week 40-50 mostly cardio is this affecting my periods? 
Can anyone relate to this? 
Thank you