How to get through 12.5 hour shifts pregnant

Hi all, I am a new grad RN still working in an LTAC as a CNA. I am supposed to transition to an RN role in June, (even though I have been licensed as an RN for a month now!) I am three months pregnant and am still expected to take only one half hour break, do a lot of heavy lifting, running around etc. with a patient load of 7-13. Anybody been there? I am so worried about my constant tachycardia and elevated (for me) BP's at work. Quitting is not an option, I need this job as it is the only one that has responded to my RN applications. I live in Boston and there are just NO jobs here for new grad ASNs. I should be doing a bit less physical labor in a month when I transition to an RN role, but in the mean time I feel like I am hurting my baby.
Thanks for the help.
This will be closed.. as it is seeking medical advice.Just want to support you.. I worked in that capacity until delivery.. all was well.Good luck.