I'm sorry. Considering the size difference in particular you may want to consider speaking to the vet about a spay and termination as an alternative to her continuing with the pregnancy. That is her (and yours) best and safest option. If you want to try and continue with the pregnancy she will most likely require a c-section at a minimum.
There would be an additional fee for the spay but nowhere near as expensive as continuing with the pregnancy and caring for everyone properly and you don't have to worry about pregnancy and any of it's risks ever again or the pups you produce, no more seasons and she'll be healthier with a longer life span. Good luck whatever you decide.
q3525724.html#a2810229
q8997030.html
http://www.irvinevetservices.com/education_spaying.php
http://amsc.us/
There would be an additional fee for the spay but nowhere near as expensive as continuing with the pregnancy and caring for everyone properly and you don't have to worry about pregnancy and any of it's risks ever again or the pups you produce, no more seasons and she'll be healthier with a longer life span. Good luck whatever you decide.
q3525724.html#a2810229
q8997030.html
http://www.irvinevetservices.com/education_spaying.php
http://amsc.us/