I was goinh threw this too! My 4yr old was wanting to know everything she's been to like all of my app and ultrasounds also my 2nd was so fast we were worried she would be the only one close when I wennt into labor.
I was telling her that we ask God for the baby and he puts it in moms tummy (she isn't old enought to know more then that and as you my mom was waaaay to open about things growing up) but we did tell her the truth about how baby comes out. She also watched baby story (guessing the same as one born every min?) She knows there will come a time when brother will be ready and mom will be in a bunch of pain and hell come out of my girl parts. That was enough for her. She did ask why the baby was covered in all that gross stuff when it came out when we were watching baby story. I didn't know what to say so I told her its like lotion lol and the drs clean the baby up after. Lol
Aging like you mom was waaaaaay to open with us so keeping some things under hush is ok till they get older also that being said my cousin is also pregnant and her daught had just turn 9 she told her mom she knows she's had sex at lest 3 times
once to make her once to make sister and she heard them one time (small house they thought she was asleep lol)