How do I know I'm improving?

Today is Thanksgiving and I have a lot to be thankful for. I have a wonderful wife and two wonderful kids and am quite blessed.
I'm back in Laredo waiting to go to work again. My bjj continues to improve, at least I think it does. My game has really slowed down and I am starting to make it harder for better players to sub me and get position on me. I am doing better against the fellas with stripes and I am not tiring as easily. My only real concern is that I'm so much bigger than the people I roll with I can't really judge where I am at. I'm usually 40-50 lbs heavier than everyone else. I don't know if it is just my instructors or the fact they are Brazilian or what but they are tight with the criticism. I think I am going in the right direction (I only concentrate on sweeps and defense and try to make everything else secondary). I only hope that I don't make unrealistic expectations for my self. I don't want a belt or stripes, I just want to know if what I am doing is correct tor not. This is all a mystery to me but I am reading up and I need to take the advice I give to others, and just let it happen.

First post

This is my first post, so here goes... I got turned on to the web site by a person on another forum. It looked like fun so I think I will try it. Pretty myopic to think that others would care to read about me but gotta get out of the stone age sometime. Right now I am in Laredo, Texas waiting to go to work. I'm an engineer for the railroad and while it pays well it is a demanding lifestyle. While subject to call the phone can ring at any time then it is time to go to work.
I was diagnosed with type II diabetes and was told to lose weight and start taking pills. I've lost about 40 lbs in the last 3 months (I'm down to 220) and have about 10 solid lbs to go. I needed something to help keep the weight off and discovered a brazilian jiu-jitsu academy close to where I live. I had always had an interest in grappling so decided to try it. I LOVE it. At 38 I'm starting to doubt if I can still do athletic activities at a decent level. I ran track at the division I level and now that I've lost the weight and am doing something physical I am thinking of entering a bjj tournament. I've been doing this for two and a half months but want to see where I am at. There won't be that many if at all in my division so I like my chances, but with work I only make money when I work so if I have to take a lot of time off I won't do it.
I train at powerteam bjj (www.powerteambjj.com) in San Antonio under Sergio Correa, a three stripe black belt. I go in the mornings usually because the students are closer to my age and are not as aggressive, and one of my kids is in school so I don't miss any time with him. I might start fitting in a few night classes just to roll with younger guys.
Gonna post to see what it looks like.