Vbac question

I really want a vbac but I'm starting to get scared he is going to be big. At my last ultrasound, 30 week 4 days he was measuring 3lbs 15oz. If he continues to gain half a pound a week he is going to be pretty big. Does that increase the risk of tearing? My daughter was only 2lbs 11oz when she was born via emergency c-section so does that mean since my uterus has to stretch more this time it's higher risk? I plan on talking to my midwife on my appointment on Monday but I'm looking for people who have gone through this or are going through the same thing now.