I say still get the measurements done, there seems to be a slight risk with not getting them done....
the idea and fear of a big baby is something you will have to change. I always measured to date however my gp and a couple other medical professionals suggested that i may have to get a scan to see the size of the baby cuz i might be too small to deliver vaginally. Pre-pregnancy i weighed 45kg and am a size 6. I put on 15kg with my pregnancy and it was all baby related. I was determined to give birth and not have a c-section nor be bullied into any pain relief etc. Even if i had a big baby I wanted to PROVE that I could do it....with that mindset i took the advice from doctors and respectfully declined.
I went on to have an 8lb 2oz baby with no tears! I was quite shocked at how big bub actually was, but i am so proud of myself for doing it! If your midwife will not support your choice for a vbac then change midwives...she will be supporting you in the most stressful time and you dont want to be pressured rather than supported.
all the best