Hi Andy and welcome to the community. It’s great that you have come so far as to walk unaided and I dare say much of your tiredness is still brain fatigue.
It was at about 18mths post stroke that I decided I needed something more than just walking if I ever wanted to improve beyond the very basics. I now needed something more to improve balance and stability so I could speed up a bit and walk for longer. Walking alone is never going to be enough to build strength, stamina and endurance. That’s when I joined a local strength & balance class once a week, which is run by Age UK for the over 50’s age group. But you may be able to find something similar in your area because it sounds like that’s the stage you are at. I also attend a body balance class also by AgeUK which is held at a gym with one of their instructors and is a lot more advanced. I also go to another gym a couple days a week to basically do my own thing.
We lose a lot of muscle mass post stroke, mainly because we spend much time either sitting or lying down, unable to walk or do much else. That loss has to be built back up and walking alone is not going to be enough to do that. There are many little exercises you can do at home to strengthen your legs and hip flexors to improve your walking ability and gait.
Not knowing your age or your current level of ability, here’s a few good basics:
Sit to stand (Squats): And all you need is a chair. Sit down and stand up 10 times then rest for a minute; keeping your feet hip width apart. Then do 2 more rounds of 10 with a minute’s rest between each. If you can’t do 10 reps then only do 5, you can always increase as you improve.
Part of our fear of falling, aside from injury, is being stuck on the ground, floundering around like a beached whale, because we can’t get ourselves back up again.
The way we were taught at Age UK is to stand up and face your chair or bed.
Place both hands on the chair seat and take a few steps back.
Go down one your knees, one knee at a time with your hands supporting you on the chair.
Walk backwards on your knees until you can bring your hand/s comfortably to floor.
From being on your hand/s and knees its much easier to crawl backwards/forwards into a more roomier position to lower yourself prone onto the floor.
Lower your hip first, then down onto your elbow and from there you’ll find it much easier to lower yourself down to your side and then roll onto your back on the floor.
Once on the floor, do give yourself a full minute’s rest before you reverse the process to get back up again. It’s not a race remember! 
And the rest is not for you, it’s for your muscles! 
So to get back up from the prone position, role onto your side again.
Bring yourself up onto your elbow first, then your hand so you’re sitting on one hip.
From there you can role onto your hand/s and knees
Once there you can crawl back to the chair/bed then use your hands to help lever yourself back up.
This technique also gives you a good bit of an upper and lower body workout in the process 
And hats off to @Bobbi who has just created a video of him doing that manouver himself. At the age of 80 he’s managed to get down to the floor and back up again with the use of only one arm and one leg. If he can do it, anyone can, it’s just a matter of putting your mind to it And it’s a good confidence builder for when you are out walking.
There are loads of little hip flexion exercises you could, it’s just a matter of keying those words into google a picking out the simplest and best for suite your ability.
Such as marching on the spot, raising each knee to hip height, hold onto something for balance if needed.
Here’s two more that are one good for hips/lower back and so improve walking. You can put a cushion under your knee for comfort.
This second one is a good one to one to do first thing in the morning before you get of bed, more comfortable too
Lorraine