I'm confused. You're a week from AF? That would mean you have an 18 day lp, and that seems really long. I'm not an expert but I have never heard of one that long.
Yes, implant can range from 5-12dpo but it is more likely 6-11 with 9 being most common. I have always implanted early (6ish). I just don't believe in inflating hope/sugar coating. I've never had spotting that late turn into a bfp, but that is just my experience.
I also don't like to use never anymore. Ladies on here when I first joined used to tell me you're regular until you're not and it drove me nuts at the time... But now I understand what they mean.
I don't know much/anything about clomid so take my opinion with a grain of salt. I do hope you get your bfp.