should i stop work early?

i'm currently working as a teacher in a childcare and is in class with the children for a big chunk of the day. i know most pregnant ladies are able to work up till 30+ weeks but i come back so tired and drained from being in a classroom filled with so many active children everyday. my second trimester hasn't been as enjoyable as i've read it's supposed to be for most, since my lethargy and a few other pregnancy symptoms have actually intensified (breathlessness, irritability, migraines from the loud ambience, etc.) doesn't help that the last term of school will be soooo hectic what's bothering me too is that i will be moving houses soon and be further away from work closer to my third trim. but with everyone i know and seen so far working till the start of their maternity leave i feel so useless if i took on the option to go on unpaid leave for the time being....