Do you think it's ok for me to wear a bra that's a bit too big?

I wouldnt go out and buy anymore bras bigger than your normal size. if you wear it ALL the time your girls will start to sagg. i also wouldnt wear it with shirts that are low so when you bend down no one will see the extra space your girls are living in. Also adjust the bra straps. but i would insist on always getting your exact size and doubling checking so you wont make the same mistake! :)