Work related exhaustion

Not sure whether I’m looking for advice or just to rant 😅 32+4weeks, have a 2.5 year old, work as a secondary school teacher with a TLR. I roughly get 1 “free” a day and usually spend that hour chasing statements from children around the school for different situations. At the beginning of the term there were more than one member of staff who were pregnant but were not given a timetable due to leaving at the end of September and before half term - a member of staff even being allowed to WFH 2-3 days a week. However, I’m now further along and have been given no support whatsoever despite explaining and having meetings how exhausted I am. I finish work each day with my bump and back so sore, usually in tears on the drive home, then home to play with my toddler before bed before I can even sit down. I took today off as I’m so exhausted and you have to give a “reason” why you’re off on the phone before you send cover work in and I’m so worried that if I need to take another day this half term they’ll say I need to start maternity early at 36. Even though I’m trying to hold out until the end of term. I’m not sure what to do - keep taking days where I need them or fight for further support at work. Anyone else in a similar situation?