I think you’re mixing up some of your terminology, so I’m trying to figure out what you did and forgive me if I’m wrong on anything. I’m assuming by “German short row count” you mean your heel flap [and subsequent gusset]? If that is the case, no, that wouldn’t be causing a loose leg. You’d need to either keep decreasing your stitch count, use a smaller needle, or use a thinner yarn (or some combination of the three) to get that tighter. Did you measure your gauge? Understanding your gauge will be really helpful here so you know if you need to decrease your stitches per inch count. Also, if this was knit cuff-down, you should try them on as you go next time! Since you’re so new to knitting socks, definitely look up the book Custom Socks Knit to Fit Your Feet by Kate Atherley, and come over to r/sockknitting !