I can certainly relate.
The first thing I’d like to suggest is letting the CC know about the difficulties you’re facing and see if they can help you out.
Second, teach your helper how to baby wear. Whether she picks your toddler up or not, very good and useful skill.
A third option - expensive no doubt- would be to send your helper by grab to pick your toddler and back on rainy days. As for days with good weather, do a run through. Have your helper learn to get up the bus with a baby and a stroller.
Yet another way, make friends with your child’s school’s parents. Perhaps someone who drives can help you out by dropping your LO back home and your helper can come downstairs to receive your tot? Then you can make personal arrangements like giving a monthly fee or trade a skill.