My Onco is more worried about my blood counts and organ functions. She already knows my breast had cancer. Now she is worried that it has spread. Breast exams are the responsibility of the surgeon and mammogram people.

Yes I personally would do. I actually did it. Yes, I had circulating tumor cells in my blood. The takeaway is that now I’m focused on doing what I can to live a healthy lifestyle: this means fasting for 36 hours once or twice a month, avoiding sugar , taking high quality supplements (especially Curcumin, Quercetin, Vit C, polyphenols, mushrooms etc). Also sports lowers risk by 50-60%. I also read that over 400 clinical trials are ongoing where they use hydrochloroquine (yes that’s the touted Covid drug) or chloroquine in seeing how it can eliminate those CTC cells. If you google it, you can find those studies. It’s not just some obscure clinics, it’s Penn Medical, it’s John Hopkins etc. So, I’ve been considering to actually take it because when you have those CTCs, especially over the threshold of 1 CTC per 7.5ml, recurrence risk is high.

I'm referring to Signatera.
Currently I see my Oncologist with no testing, she doesn't even check my breasts.

Would you suggest doing the blood test? Are there other treatments I should do?

Are you referring to liquid biopsy blood test, or cancer marker tests? You do need regular follow-up for sure (every 3 months).