Everything you say is what most ladies feel and I can relate completely to you. You're not mad, or paranoid...just coming to terms with what has happened to your body.
I had a double mastectomy last October with recon and thankfully I havent needed chemo or radiotherapy... i too am on Tamoxifen and apart from hot flushes I think i'm ok.
I think it is after all the surgeries are done and you don't have that to focus on that you start to think more about it all. I know what to say to people, I know what I should be doing...but I still worry that IT will come back.
My BC nurse was going to refer me to a councellor but the appointment never came!!! Having good friends to talk to does help and reading ladies comments here does too.
I hope you manage to move on, talk to your BC nurse for advice,
Take care and keep in touch
love Erica x