Hi @Cobi, welcome to the blog!!
Like you, I was diagnosed with ILC that was missed both by Breast Screen NSW and the followup Mammogram/Ultrasound at a local radiology place .... tho they DID suggest a biopsy be performed, which confirmed the presence of Cancer cells in 2 lesions. I also have reduced faith in the scans.
I had a Lumpectomy, followed by radiation & been on AIs for 6 years (I finish next year.)
Since my diagnosis, I've travelled to Port Macquarie every year to a Radiology place who has a dedicated female Mammogram and Ultrasounder who specialises in Breast Cancer. I have total faith in her.
I hope you can find a similar place in Qld - as you may have ongoing Ultrasounds for the remaining tissue on your chest? xx. Take care