I dont think its just the strain..those dont even look halfway done. There are sativas that take like 16-18 weeks to flower but theyre too expensive and impractical for most to grow indoors so its highly doubtful a strain like that just happened to be in circulation among growers around you,especially without the person you bought them from telling you so.
Are your timers okay? Have you peeked in to see that the dark period is still a full 12 hours each night? I ask because a while back, a friend of mines battery went out on his timer around week 2 or 3 of flower. The lights stayed on but never went off. He would just go in during normal light period (not knowing there was no dark period) and started noticing the plants buds werent progressing. They looked a lot like yours.
Anyhow,if it isnt something to do with the timer screwing up..I would probably trash them. I know that sucks but theyre not really doing anything except using up your time and resources, and there is no guarantee that youll have much bud in the end. Best of luck to you