Respectfully, your response makes me believe you absolutely need to pursue a medical profile while you process through IDES.
We sometimes forget that while as individuals we are important to the system and our job at that moment, but we also must all be replaceable for the system to function. Doing my job correctly was to set my subordinates up for success as well as my replacement. Being indispensable is not that way in the military. I know that can be hard. And from your comments you have served and dedicated yourself as an ideal service member. Even if you are not there and they become shorthanded, it will be okay. I was told this from a COL some time ago, you have done your job and you have done enough. It's time to let go. I believe it may be your turn to hear that.
I suggest making a personal statement about your stressors both physically and mentally while especially mentioning your past history of pregnancy. Describe your worst times on paper as short and as best you can. Then take that to mental health. Discuss with them about a limiting medical profile while you go through this process and pregnancy. You will not be the first I promise. You can also alert your commander that you would like to see military mental health. That is not necessary as I understand that can be uncomfortable, but it could help. Definitely put that in writing if you do request that of your CMD. Paper trails will help you in the long run. Remember, at this stage it is about you, your pregnancy and your family. Those come first now. You served your country and did your job. The system will carry on without us which means we did our jobs.
Added after I replied - reread your first post. You mentioned being processed for mental health. If that is the case it is likely you have a medical profile already or should have one that triggered you to be in the MEB/PEB system. For the Army it is a DA 3349 P3 Profile. Take a look at that. Remember, if months from now after the investigative process they say you are medically retired, then that means it is also true today that you medically cannot continue to serve. It's okay to go on a limiting profile while you wait for the process.
I wish you the best no matter what path you take.