IUI and progesterone suppository ques. ???

Brittany
I just had my first <a href="https://glowing.com/glow-fertility-program">IUI</a> done on Friday. I'm currently on progesterone suppositories.... I've had some cramping and my lower back has been sore as well. Is any of this due to the <a href="https://glowing.com/glow-fertility-program">IUI</a> or suppositories??? Or could it be implantation or ovulation?? I'm currently on CD 16. 
Also, how do I read what sizes my follicles were... D1 D2... Etc. 
Any help would appreciated for this is first "real round". First time I took clomid my follicles were t mature so it was a no go.