I am sorry to hear that you are going through this and I understand your frustration with this requirement as I am in the same boat.
I think you have a good chance of getting a waiver. It requires some "creativity" to present your case. I assume your son is a U.S. citizen so you can show that a hardship will be experienced by two qualifying American relatives. What I mean by creativity is that you need to expand on your reasoning for claiming a hardship. For example, maybe your son's diagnosis is not enough for them to grant a waiver but you having to leave your son to satisfy the requirement will constitute an exceptional hardship. Or should you choose to leave with your son for the Phillippines, this may cause an emotional hardship on both your husband and son etc. As for pregnancy, I do not think USCIS considers it as grounds for an expedite but maybe you can get a letter from your therapist stating that you leaving for the Phillipines will be detrimental to your emotional state etc. Maybe your husband's stay in Japan is coming to an end soon and they are sending him to the U.S. which I guess can be good grounds for an exceptional hardship too. You can also look into your country's conditions: level of pollution, crime rate, healthcare system etc; anything that could affect your qualifying relatives' wellbeing while they are there with you. I hope my flow of thoughts makes sense to you. You do not have to have one solid argument for an exceptional hardship, there can be 10 small ones.
For the exceptional hardship you need to present two cases basically: what will hapen if I leave my U.S. relatives and go satisfy this requirement by myself and what will happen if my qualifying relatives come with me to the Phillipines.
It is also important to not focus on yourself much when applying for this waiver because they do not really care about our hardship, they do care about the hardship your qualifying American relative will have.
As for that couple that expedited their case. Unfortunately, I do not know much. All I know that her husband had his superior call USCIS and then DOS for the expedite or something. I believe there is a USCIS military line so maybe they will help you guys understand better how it works.
I am not sure if I can attach links in this post or advertise one's Youtube channel. But there is a lawyer on youtube that specializes in J1 waivers and if you can watch a handful of his videos you can get a better idea of how to navigate thru this process and what arguments you can use to make your case stronger.There is not many lawyers talking about J1 waivers so I am sure it will be easy to find him on youtube. Back in the day I also found this mannual on this very website that talked about J1 hardships in depth. I can't send the link because It has been a while but I am sure you will find it in one of the J1 waiver threads.
Good luck!