Combination of things - firstly tights and cross dressing, plus (let's be honest) watching porn and stumbling across adults in nappies and realising that was a thing, then becoming inquisitive and concluding that wetting in my house wasn't an option that if I wanted to wet I'd have to do it in a nappy. Bought a sample pack of 2 off the internet and discovered I loved the feeling of the padding between my legs - I'd been looking for that wearing tights, but they weren't quite hitting the spot - together they were awesome. I also remembered aged about 4 trying on my old baby nappies that were left in the airing cupboard in my room, couldn't get the tabs to stick, but something of that experiment stuck.
I've spent a bit of time travelling around the country, so was in a position to buy, or dare myself to buy some products like pull ups where nobody knew me and build up to buying Tena Slips late at night in my local Asda and then eventually Tena Slip Maxis off the internet. During that last part, Covid hit so spending time at home alone wasn't a problem and it was one of the ways I got through the various lockdowns.