Confused ttc baby#1 bfp? 17dpiui IUI#1

Hi All, 
So getting more more confused till my doctor appt. Right now 17dpiui and AF was due 7/14. She hasn't arrived in full form yet but the past two days I've had some light brownish red spotting :( really hope this bean sticks. I'm hoping it's just growing pains but who knows never been this far down this road. Boobs are super sore and have been for 3 days. Lower back aching come and goes feels like AF is coming but idk. Also I'm checking to see if my lines are getting darker and they look like they are, at least I think they are.. Let me know what you think.