I first want to start off by saying that I'm so sorry for your loss. I was shocked as I was reading your post because we have so many similarities! I too lost my baby boy at exactly 20 weeks in April. My OBGYN also diagnosed me with an IC, even though she didn't deliver my baby. She consulted with the doctor that did deliver and that was the conclusion. The day I had my baby was a Saturday. That previous Monday, I had an appt, and literally, everything was fine. We even found out the gender. My pregnancy was also perfect!
What happened was I started leaking fluid that Thursday and I just thought I was experiencing some bladder incontinence. It wasn't until that Saturday when I started spotting that I called my doctor's office and they told me to go to the hospital. Meanwhile, the whole day I was having contractions and thought it was my baby kicking or moving around. When I got to the hospital, they tested the fluid, and it was in fact amniotic fluid. My nurse checked my cervix and felt a bulging bag (which you also mentioned). The sonogram tech did an ultrasound and Baby Boy had a strong heartbeat. I had dilated 2.5cm. I honestly didn't understand what was happening until my nurse kindly shared that my water had broken and I was going to deliver my baby that night. They induced my labor with Pitocin and I had my baby around 11 that night. My Mom and Sister came and my Son's father was with me the whole time. My Baby Boy, Carter, lived for about an hour before passing in my arms.
I still have so many questions about what caused me to have my baby so early! The nurses told me I had developed a uterine infection because the fluid had been leaking so long. They never said what type of infection, but they made it seem pretty bad as in a time sensitive issue. They made it seem like if I hadn't come in to the hospital that day, something would've happened to me. I also have a history of UTIs and had an abnormal pap smear result in February and wonder if that could've caused PPROM. I don't disagree with my OBGYN, but I think that it's deeper than just having an IC. My OBGYN has pretty much ruled out anything other than an IC and so I'm requesting my medical records from the hospital to see if that can lead to some insight on my situation. I think finding answers, if any, will help with my grief journey and provide some closure.
To answer your question about contractions, mine were pretty intense before I went to the hospital. They were also frequent on the way to the hospital, and I can't remember after they induced my labor. I was on "happy" meds. I believe your condition could be both IC and preterm labor. I don't think your age was a factor!
Sending you lots of love and healing and I hope I showed you that you are not alone!