Ugh! People just repeat the rubbish they hear. It might not help you feel better, but sounds like she was really just trying to say something supportive...even if it just made you feel worse IYKWIM. Maybe, if you want to educate her a bit , you could write a letter to the practice and say that their receptionist gave you 'advice' that left you feeling offended and flabbergasted. They might then have a word to their staff about being sympathetic only, in situations where they don't actually have a clue what they're talking about. I think you'd probably rather hear "oh, you poor thing, good luck", and it sort of sound hollow and unhelpful, than to have what was effectively a kick in the guts due to ignorance. If you say nothing, she will think her advice is gold and dish it out to someone else who she overhears of having conception issues, but if you write a letter, there's at least one other person who knows better.
Hell, just go on the holiday anyway and recharge