Yep it's normal! If the cramping gets severe you might want to call your doctor. The cramps are a sign of your uterus stretching to make room for baby. :)
My due date is also sept 25 :) but i get cramps really bad sometimes especially when im constipated sorry tmi lol but dr said it was normal. And back has been hurting for like a week now but he also said that normal. As long as you dont have any spotting or major bleeding i think you will be just fine! Good luck!
Yes it is very normal my doctor told me your lower back hurts alot because of the streching of your uterus