Erika888 ... What is causing your reluctance to take Letrozole? Your medical team is making decisions that will hopefully benefit you in the long term.
The main reason for taking AIs is to try & prevent a cancer recurrence ...
So it would probably be in your best interests to give them a go as your Oncologist has prescribed them for you, for a reason. If you aren't comfortable talking to your Oncologist about it, maybe chat with your Breast Care Nurse? Or even ring our Helpline tomorrow on 1800 500 258.
Having a bone density test prior to starting AIs is pretty standard - and continuing exercise is always good, as is watching your diet. Some supplements can inhibit the AIs - Tumeric/Curcumin has been mentioned - so always put any supplements past your Onc. Excess Vit B6 can cause neuropathy and additional aches & pains .. ;) (Copy & paste this link)
https://onlinenetwork.bcna.org.au/discussions/general-lifestyle-and-wellbeing/peripheral-neuropathy-aches-and-vitamin-supplements--caution-about-b6/
Very Regular blood tests are usually done for chemo patients re red/white cell counts before every dose ....
Most GPs won't order 'excess' blood tests unless there is a specific reason. Many won't 'do' Cancer Markers either.
Take care & all the best.