...too tight jeans are bad for your lower back - can put it out. I like wearing skinny jeans, but I have back probs and a chiropractor told me this years ago... but mostly I hated the feel of anthing tight against my lower ab.
You should be able to pick up something now that will last you right through. The sizing is based on your pre preg size usually, so its not like you need to wait and see how big you`ll get before you make a purchase.