So sorry to hear this. Like everyone says "hang in" and stick with your vet if you have confidence in the - if not get another opinion
I have a 4 year old that is considered very small. She gets only one shot a month apart, ONLY. Do read Dr Dodds article.
Frankly, starting this year I only titer and am working on a vet waiver for rabies. I'm sure others here on YT can give you there experience and thoughts. You have come to a group with a wealth of experience and willingness to share
Will be thinking about you and Martini with prayers!