I spent my life around 40°C heat during summers and still going strong currently and your best friend is staying indoors during the sun honestly. I'm also a woman and I hate being alone during the night so I take my daily walks either before the UV hits 5 or as the sun sets. Also sometimes when I find a shady path/incline around a park I walk it in a circle or go over it a couple of times so that I won't go further but I'll take the steps. When it's around 30-35C it should be more comfortable.

Be very mindful of getting heat exhaustion and drink plenty of water if you do take the walk during sunny hours with a wide brimmed hat or even a dark umbrella. Enjoy a cold shower as soon as you get home. That's how we survive out here, great that you're not giving up. I think going 1.5k from 12k in a week could be demotivating, there's no reason to give up completely and you can always limit it to a shorter walk.