This wasn’t lockdown and not for weight loss, but still relevant as it relates to fitting exercise in under single parent conditions. When DS was a toddler DP was seriously injured and out of action for 18 months.
I’m a cyclist anyway and already had a trailer for DS (DP had towed him). I knew the only way I’d get exercise in was to bring him (DS obviously haha) along for the ride. Where I live is very hilly, so I had a different cassette fitted to my bike so I could cope towing. I took DS out several times a week. I’d pop a picnic in for summer (couldn’t afford cafes) and a flask for winter. I was already fit, but this made me even fitter!! I took him out in all conditions (apart from ice!). DS balance biked from 18 months. So by the time he was 2.5 he managed 4 miles (broken into 2 miles, rest, then 2 miles). I’d push him with a long stick when he got tired. But, it meant I was able to run while he balance biked.
I’d cycle commute DS to nursery so I fitted a ride in on my work days. Alternatively if I needed the car, I’d pop my bike in the night before and get my kit and work clothes ready… then drop him off at nursery the second the doors opened. It then gave me 50 minutes to ride before work and 40 minutes after.
Is your toddler still napping? If so use that time for exercise. I’d have my bike setup on my rollers (like a treadmill for a bike), my kit on etc. Then as soon as DS went down, straight on my rollers for 90 minutes. I’d also get various friends to pop over for an hour or so of an evening once he was in bed whilst I went out for a run or ride. I neglected the housework as I knew I needed to be happy, that endorphin rush and feeling fit makes me happy! I basically prioritised exercise but fitted DS in.
I still involve DS in my exercise… amazing I can still tow him - he’s now 5 and still loves a trailer ride. But I have various other ‘gadgets’ to enable me to cycle with him. He’s also fit enough to ride with me independently, albeit very slowly. But it’s magic riding with him.
Yeah so, in my experience having a small child and being on your own isn’t a barrier to exercise. You just have to be creative, think outside the box a bit and prioritise it. I’d plan out what I was going to do the week before and kept it varied.
I’m also in the diet for weight loss camp! The one thing that makes a difference to me is cutting out the evening snacks. I have to eat the calories I burn exercising, or I’d never recover from the efforts and never be sufficiently fuelled for the next one. I also pick colds up easily when I’m not eating properly (enough). You don’t sound like you are eating very much in your description of your diet - could that be why you aren’t losing?