Brenda how would you tell if it was working or not? That's the biggest issue. Unlike the other drugs where you can see changes and monitor. The only way with tamoxifen to know if not enough is if the breast cancer returns. If really wanting an alternative to it perhaps its time to revisit changing to an AI instead.
You need to discuss the reduced dose with your Doctor. Drug sensitive is different really to supressing hormones. I know for instance with letrozole...all women on same dose. ..whether they have huge amounts of body fat or not. The medication is not weight dependent or symptom dependent like other medications.