Yep... if every day is "bliss" then they are lying

I think if you are having a rough time of it and really need to let it out it might help to phrase it like "geeze I'm having a struggle with such-and-such this week... I know it'll pass but it's hard when your in it". Or "I'm not saying this will happen for you when you have your baby but...." KWIM? If you can reinforce that your intent is not to bring her down with warnings of doom then she might be a bit more supportive.