I agree that Meghan's style is a bit edgier, and suits her personality. I think that getting pregnant so soon (which I still believe was one of those hilarious "your fertility fell off a cliff 2 years ago when you turned 35 so get busy the night of the wedding" pregnancies where the poor woman is gobsmacked to discover it's totally possible as a 37 year old to get pregnant in less than three months), completely threw her. She strikes me as extremely organised naturally so I would not be surprised if she had been at least thinking about potential outfits at leat until the end of 2018, most of which then had to be thrown out because of the baby.
When she is dressing for her natural style and shape, she always looks amazing - that armani suit before they got married, the green leather skirt combo etc.
And where the "untidy" idea comes from is completely beyond me. She might wear her hair in looser arrangements than Kate, but she's the complete opposite of untidy. Her outfits tend to be crisp, her make up and hair sleek and her nails glamourous.