Welcome to 3FC, I hope you stick around, it's been an amazing source of comfort, advice, and support throughout my journey.
That's great that you're walking! When it comes to exercise the best thing to do is something that you'll stick with and do consistently! It sounds like walking works for you so keep up the good work! If you feel like you want to try new things check out the exercise forum on here. Personally, I swim and weight lift and have learned to love it (I have some injuries so that's about it when it comes to what I can do).
As for the diet. Well, I agree with finding something that will be easier to stick to long term. I've lost a good chunk of weight making small changes in my diet (little to no sugar/artificial sweeteners, eating only who grains, lots of fruits/veggies/meat etc). Some lose well with calorie counting, others on the South Beach diet. Ultimately, you need to find something that works well for you. Something you feel like you can stick to for the rest of your life. It's taken me a lot of experimenting but I feel like I've found that. Don't be afraid to change things up every now and then either. As long as you're eating at a calorie deficit and exercising you're on the right track and WILL get to your goal.
I'm not one of those women who was healthy at my highest weight. That being said, I had health problem then that I never realized I had because I had gotten used to them. After losing the weight I noticed that:
-I sleep better at night, less insomnia
-I have more energy, even work related things
-I'm also better organized.
-My allergies seem to affect me less
So maybe with weight loss even if your cholesterol and everything checks out you'll find some other benefits.
Oh, and also have a daughter and I can relate. She definitely was a big motivation for me and this journey.