Any advice for me?

A very good question !!.  

American Urological Association (AUA) guidelines recommend the surveillance after treatment  as follows.

If the initial diagnosis was high risk non muscle invasive bladder cancers, i.e.  T1HG or CIS, which I think was your case. 
• Cystoscopy at 3 months
• Subsequent cystoscopy every 3–4 months for 2 years
• Then every 6 months until 5 years
• Life-long annual cystoscopies thereafter

European Association of Urology (EAU) guidelines have similar recommendation with life-long annual cystoscopies.

National Comprehensive Cancer Network (NCCN) guidelines say 10 year annual cystoscopies, then shared decision on surveillance.

www.ncbi.nlm.nih.gov/pmc/articles/PMC8261410/

Diagnosed four years ago.  Had Turbt, then bcg.  Since then I've had all sorts of mris, ct scans, cystos, etc. Even had my first PET scan, which was negative.  My FISH keeps saying abnormal chromosomes and bladder cancer, but in four years I've not had any new tumors.  Just had another cysto last Friday and bladder still clean. Do I just keep getting the cystos?  I was on a three month schedule, now on a 6 month schedule.  I had some reviews by an oncologist and he said he can't do anything for me unless/until I have a new tumor.