I had the same thing happen after losing 70 lbs the first time and 40 the second. I had to buy a whole bunch of clothes sizes back again that I gave away. However I was lucky in that I didn't gain all the way back up to my max sizes. My rule is keep 3 sizes bigger than your current size, never throw out your skinny clothes...EVER, and when you've kept the weight off for more than 4 years you can safely get rid of the highest size you kept, box up the remainder and keep until you've kept the weight off for 10 years, then donate freely up to 1 size larger than you currently are (always keep one size larger just for bloating, holiday indulgence, being laid up for awhile etc)

My hubby & mother always gripe at me about how many pairs of jeans and shorts I own. I currently wear a size 12-14 (somewhere in between actually) but I have sizes in my closet (boxed or otherwise) from size 8 to size 18 (which at one time I had sizes up to 24)