GMO for sure, haven't tried the UK Cheese but I would definitely grab that if it's really the original cut. The rest really depends on the prices I'd rather grab seeds than buy clones from somewhere like Strainly they just want too much money. $20 per cut or so I'd probably grab 10 or so.
Sensi Seeds... Lol, probably Dutch passion though they have a lot more interesting strains, but Bubblegum and AK-47 for Serious.
They're all okay, just depends what you're after.
You must have severely stunted them. From mid March to now you should be more like 2 feet tall. When it comes to age that's not bad timing to start flowering. What you did to only get 4 inches in 45 days or so is the issue, could have been a runt, but my money is on too cold and probably too wet...