Late pregnancy transabdominal ultrasounds on goats

Good evening, I have a question about this type of ultrasound. Is it very accurate at 4+ months? Has anyone had a false negative? I have a doe who is 5, that had triplets 3 years ago. I ran her with a proven buck (same as last time) from Oct. 2 to Nov. 6, which puts her due from Feb. 24 up to April 10. She is a very hairy, deep carrying fainting goat. No udder yet. She lives with her two 3 year old does and 3 wethers. When the younger girls are in heat she also displays some signs of heat during their last two cycles that I've noticed. I was thinking she was feeding off their hormones in addition to her pregnancy hormones. Have any of you ever had a pregnant doe display heat signs? I finally broke down and took her to my local vet that specializes in horses on Friday for an ultrasound. She determined not pregnant. Just the ultrasound in the back of my jeep. No palpating, etc. I was shocked. She seems the same size if not bigger than last time at 3 weeks before delivering triplets. She bagged up about 3 weeks out last time and lost her plug over the course of a month. Anyway, I really want her to be pregnant and explain these "flukes" away, but don't want to be on a fools errand either. Regardless, I will watch her closely until April 10 to make sure. I would never forgive myself if she kidded on a cold night outside. She was also rolling around on the ground off and on the other day in the pasture. She waddles when she walks. I can't feel babies, but I couldn't last time either. Just looking for experience and wisdom from you all. I have attached some pictures. Oh and the one of the other does that was with her and the buck kidded quads 3 days ago.

1 - 3 years ago, 3 weeks from kidding triplets
2 - October 2022 when she was in with the buck
3 - last week
4 - side view
5 - back view

Thank you in advance!