Burned out - Need advice

My husband and I have been foster parents for a few years now, and so far, have had a great experience. Our last placement (from 2 months to 1 year), we had such a wonderful experience with our foster child, and even his bio mom. Our caseworker changed 4 times due to crazy turnover, but we maintained good communication with the law guardian and our resource worker and everything went smoothly, right down to reunification. This time is very different. We have had foster placement (2 .5 year old boy) for 6 months now. This past month, bio mom's visits went to 2 full days and an overnight. This is on top of weekly visits with bio dad, coming home to us, and being in daycare (husband and I both work full-time, which has never been a problem before and has never affected our kids' care). Our child's well-being has TANKED. Constant, daily meltdowns; refusal to eat and throwing up food; has been sick with high fevers and diarrhea almost every week, which the doctor states is likely due to stress and the inability to recover because of all the change and instability; crying and throwing a fit every time we pick him up from daycare and every night when he goes to bed. Before this crazy schedule, he was a well-behaved, happy, and healthy child. Now, we are watching him deteriorate due to lack of stability and our bond with him has been significantly weakened. Caring for him has become soul-sucking and draining. On top of this, we as a family are just burnt out. I have adjusted my life and schedule as much as possible to accommodate all the stress, but I am also newly pregnant and coping with all the emotional distress has been so hard. Our caseworker has been super vague and unhelpful - first she told us he would be reunified with grandma, then dad, then she said mom in January, then mom in the beginning of March, and now she's saying it MIGHT be at the next court date at the end of March. Our child (emotionally and physically) can't go on like this for another month, and I don't know if we can either. I spoke to the supervisor, who laughed and said we need to learn how to deal with it and his reaction is typical. They are GUARANTEEING Mom will get him back and it will be "imminent", but will not even entertain the idea of requesting a more rapid reunification. As far as I know, Mom has completed everything she has to, and they're just riding out another month of visitation to make sure everything goes well. I get it, but it just doesn't seem fair to our little guy. I think I could just use encouragement that I'm not the only one who feels frustrated, and maybe advice??? The last thing I want to do is disrupt and have little guy retraumatized. BUT - we are at the end of our rope! I put a call into the law guardian to see what she says. I just don't get what's going on, if they're saying mom's doing great and will definitely be reunified "imminently" and we're saying we and little guy are suffering - WHY they laugh and say a more rapid reunification is impossible and won't be considered. Any experience with anything like this?????