First, I want to say that I can't believe that you transitioned your hair (2010) all the way to waist length. That was a lot of transitioning! You must have had the patience of JOB to deal with two textures with that volume of hair!
As a new relaxed head (3 days in) I can totally relate to what seems to be your main reason for wanting the change, amongst others....IT TAKES FOREVER!!!
That's how it was for me, so I do understand. I say nurse your natural hair back to health and then see where you stand. You don't have to relax all of the curl from your hair if you don't think you can fully depart from your curls. One of the reasons why I went back to being natural was because I wore so many textured styles with my relaxed hair that I just decided to stop relaxing it.
My decision to get relaxed after 13 years of being natural was nothing deep. I expect to miss my curls and I'm telling you, there ain't a curl left in this head. When I was natural, I had moments when I missed having straight hair that didn't take FOREVER to straighten and had some lasting power! It's like anything else, when you have this, you miss that. I wanted to relax so that I could get away from long detangling sessions, frizz, sometimes I just wanted to comb my hair and brush it, too. One of the styles that I missed wearing that I couldn't wear with my natural hair is the single french braid. My curls just would not allow me to complete the french braid without getting tangled up. But, my curls are my natural hair and I thought they were beautiful and I'll see them again, one day, when I don't want to relax anymore.
So, you have to do you. It's about what you feel, what you can deal with. I think your hair is lovely, but I'm sure relaxed is lovely, too. Take your time and decide. Remember your transition. Once you go relaxed it takes time to get back. I've added a few pics of my beloved curls.
Good Luck! And let us know what you decide.