I think your biggest "problem" is using too wide a strip of fabric for the binding. It gives you too much to fold over.
If you used a 2.5" strip, try it with a 2" strip folded--That is what works best for me. For a beginner, you might want to try a 2 1/4" inch strip first. There is no hard and fast rule on how wide to make the binding strip--experiment until you find the width that works best for you.