it has taken me 12hours. NO BREAKS. to set up 31 models :(

i am really struggling with the size of my files as they just wont merge without taking hours... im slowly trundling through it, however there is no way i am going to make the deadline at this rate as the render will probably take days! however theres nothing i can do as this is my whole project :/ and I can not start all over  just hours before it is due. I shouldve realised the problems i would have when my first files started corrupting :/ but oh well, i have definitely learnt from this mistake! i may have to do separate renders as there is no way i can get all 81 models on one file and be able to open that file on the uni computers.... it already struggles with my files containing 6 models. I have pro optimized every model to as low as it can go... but i have really sacrificed the quality when doing this :/ and even so my files are HUGE! this ones at 1.5gb