My take on it is that you have two choices when these things happen - say nothing and say something. Say nothing and nobody will realise they're hurting you so it will continue because they probably mean well so don't think of the effect it's having.
Say something and you again have two choices, hurl it back as it is, straight, to the point and walk away, or prepare something that is more skilfully worded but actually does tell people you aren't enjoying the 'joke' and want their goodwill expressed in different ways.
The former would hurt them as they've hurt you, but as you say, not help the family dynamic overall. And if you say nothing until you can't bear it any more then this is what you'll do, explode in anger one day. So if you do care, you have to find a way to tell people that will get your point across without offending but effectively asking for the pressure to be taken off before you say something you might regret as no doubt they will regret having upset you all this time whenever they actually find out that it does.
It's amazing what habits folk get into without realising the effect, nicknames, family 'jokes' and stories that nobody dreams is anything other than what it is intended to be, yet the 'clever one' tag haunts both the nominated one with pressure and the others with feelings that they're considered stupid, the 'pretty one' feels like a bimbo not appreciated for her thinking and the rest feel ugly by comparison, second rate-ism is rife in family situations and that's without who has babies first or is best daughter in law or later additions to the childhood established stuff!
Speak carefully, but speak, or nothing can change. Maybe individually rather than to the whole lot, make it personal, ask for their support and understanding of the choices you're making and maybe even mention how awful it would feel if you came to the point of trying and didn't conceive straight away.. Sometimes a future scenario works because the other person can hold the belief that they haven't done anything quite that badly wrong yet but can think through and adapt in case it does and actually improve the past/current behaviour as a result. Or they might imagine you're telling them you have been trying and daren't admit it, but it should still get the comments toned down or stopped!