Tamoxifen worries me! The side effects are quite annoying in my case. Is it really as effective as the oncologist claims in preventing the cancer from coming back?

Stage 1 grade 3 breast cancer. Taxol chemo (weekly), Herceptin and Perjeta (every 3 weeks in the UK), followed by surgery to remove the tumor bed which had completely disappeared on ultrasound after week 4 and radiotherapy for 3 weeks. Tamoxifen since the end of June, if I remember correctly. More side effects with Letrozole, hence Tamoxifen, even though I am now 55. I'm a non-smoker, no history of breast cancer in my family. I walk a lot, but I can't get back to jogging yet, the breast doesn't really swell. Edema that I hope will not remain permanently...