I've read those rumours as well, but I can't remember where - I've obviously become much too addicted to this
Possibly Blind Gossip or the Harry Markle blog (which is a fascinating rabbit hole to delve into). The timeline of events there would fit too - she turned up unexpectedly at the Invictus Games in Toronto at the end of September 2017, and there are photos of Harry (& Justin Trudeau) looking unpleasantly surprised at her arrival. Couple of days after that, she and Harry arrived together and then at the closing ceremony, Doria, Jessica Mulroney and Marcus Anderson were seen "having words" with Harry. Allegedly, this is when he was persuaded to do the decent thing because she was pregnant. Less than six weeks later she'd moved to the UK and into KP and the engagement was announced a couple of weeks after that at the end of November. All very hasty. But she wasn't obviously pregnant at the wedding six months later, so was all this conjecture, or was there a "miscarriage" somewhere along the way after the engagement...? It's the oldest trick in the book, and pretty despicable - would Harry really fall for that, and would she be that low...? (Personally, I'm not ruling anything out, and let's face it, what we've seen of her wouldn't put it beyond belief.)