you should be fine, stop worrying. if anything happens it will be you don't like it anymore as there's other fantastic stuff around. i'm not sure on lipsy sizes. i know jane norman come up very small and although i'm a 12/14 i get a 16 from there.
i'm a next 14 and a m&s 12/14.
when i started my journey after my first child, emily, i was 17 odd stone and still in maternity gear as i didn't want the reality of knowing what size i'd actually got to but i recon a 22. by the time i finished my journey feb to june i lost 4 1/2st and was then a size 14. i feel pregnant again so stopped cd. after, matthew (the dude) my 2nd and last child i was just over 15 stone. however, i ate a bit too much after him as i was feeding him and felt hungry. my weight went back up to 16 odd stone and i started ww. when he was 10 months old i stopped feeding him and started back on cd again - feb! i was just under 15st and went down to 11st 10lb before my iron levels dropped too low to continue. i hadn't got to where i really wanted to be but i was running loads and doing a half marathon.
i had a lot of stress during my absence from cd with my mum going in and out of hospital, loosing a toe, being in pain going on morphine so i drank a bit too much wine. in nov i returned to cd as my iron was ok and had put on weight and gone to 13st. from nov to dec i lost most of my weight before xmas and am almost at my 2nd goal. each time i start back i get my motivation back. you might find that taking a short break for you op is beneficial to you.
the story is long but as i went along i developed a desire for clothes and my style changed. even now there are thing i bought last time i was thinner that i'm not bothered about wearing. you need to start saving money for you new wardrobe as clothes cost a fortune
you are always going to find differing sizes in different shops too.
