3 types of cancer, how do I not live in fear?

I had Hodgkin's Lymphoma 23 years ago.  Was successfully treated with radiation therapy +surgery.  10years later they confirmed I had what is now considered an overdose of radiation (standard amount at the time).  It caused a chronic thyroid condition,  and receding gums,  half my teeth fell out... healthy teeth :'( .  21 years after the radiation,  I was diagnosed with invasive breast cancer and Padgets disease, both diseases  in both breasts and both nipples, caused by the radiation therapy.  (they NO LONGER administer such large doses,  they are more educated in radiation therapy now).   Chemo,  full mastectomy,  and tram flap reconstruction later,  now on tamoxifen.   I feel no anger that the radiation has had such lasting effects,  I have lived,  loved,  become a parent and for the most part I have been healthy for decades.  The doctors saved my life.  But I fear recurrence, and mostly I fear more long term complications.  I had the least amount of chemo possible and no more radiation as they now fear my heart may not stand too much more cancer treatments. I fear leukemia etc as my life has proven you CAN get secondary cancers from treatment.  I live in limbo.  If I have thrush... the docs send me for an internal ultrasound,  if I have constipation...they order a colonoscopy, their caution keeps me in this world of fear. 
 I try not to be scared,  but it is the first thing that enters my head every morning when I wake.