There's a few solutions, it depends on the dress is the best answer, some dresses are clingy so I literally strap my pump to my inner thigh using a pump belt wrapped twice, looks a bit Jane Bond but works well, or I stick it in the front of my bra, as long as it's not a low cut dress this works ok too - the issue is access as very often it's a loo visit for a bolus or your pump can be set up to do it remotely via your BG meter if required, does take some working out though, but hasn't stopped me wearing any of my dresses though, just makes it a bit more interesting, no one yet has sussed I am wearing a pump yet though whilst wearing one.