Do bras shrink easily/quickly?

During last year's Victorias Secret semi-annual sale I bought a ton of new bras in 32D.

A year later and none of them fit properly except one which was still 32D but fit kind of loose for whatever reason. I'm a college aged girl so puberty was long ago and I haven't gained weight nor am I on birth control.

My question is do bras shrink easily? I have some bras that I've washed tons and some that I rarely wear I have only washed once or twice but they all don't fit except that one that I mentioned used to be loose, but that one has been washed lots because I wear it all the time now that its the best fitting one. How can I stop my bras from shrinking?

Should I start getting 32DD now even though I have been measured as 32D?
Do bras shrink easily/quickly?
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