cervical mucus question kinda long

I'm 18 and been ttc for about a year in and off. Ever since I've started using this app I've realized I don't barely have ANY cm compared to anyone else. Not even my sister. I was on the shot back in 2012/13 when I was 14 and I only had 3 rounds of it. Before I got depo I had regular amount I remember because it used to embarrass me. What should I do ? How do I make it come back? It's been like 4 years. Plus my period is less too. I use to have the normal 7 days medium bleeding. Now I have 4 days medium-light  plz help.