Clothes are getting too tight too early?!

First pregnancy only 6weeks but my jeans aren't fitting and I feel huge (even though you can't tell I'm pregnant) . I feel like my hips got wider (hence horrible back aches) and it doesn't help that I'm short and was already overweight. I feel like it's too soon to buy maternity clothes but I also don't want to buy regular jeans and then not fit in a few weeks... it's uncomfortable walking around with unbuttoned pants. Any suggestions, anyone else going through the same thing?