Firstly, sorry to hear you’re in the same ‘boat’ as many of us on here are, or have been. It is a shock, isn’t it! I didn’t have a hysterectomy either, and the reason was that mine has spread beyond the cervix… doing a hysterectomy can disturb cells and make the possibility of the cancer metastasising greater - plus at that stage you have to treat the whole body systemically. The MRi (and probably a PET/CT as well) will tell your healthcare team whether it has spread at all - possibly into lymph nodes, as mine had, and they need to treat the body systemically - kill all and every indication of cancer. I’m guessing you haven’t had confirmation of the stage so far, so they’re being cautious in the treatment suggestion.
Being set for chemo-rads doesn’t necessarily mean your cancer has spread, however. Adenocarcinomas are fast growing compared to squamous carcinomas, and are higher up in the cervix in the glandular tissue. It may be that your team are being particularly cautious overall and want to make sure they kill that tumour with a two-pronged attack - chemo and radiotherapy. These things are very good at the job! I had a primary tumour in the cervix plus cancer in the para-aortic lymph nodes (up your belly) and was Stage 3 squamous cell carcinoma. By week 5 of the treatment I had a PET/CT (I was part of a voluntary research study) and the lymph nodes were clear! The next scan was 3 months after the end of radiotherapy (this keeps on working in your body for 3 months) there was NED - no evidence of disease - so the tumour had been eliminated. This is what they’re working towards for you.
Try not to panic - I am 64, so a lot older than you - and (if you see my back story) first had rogue cells when I was about your age, but then only had LLETZs and cone biopsy - and it returned, unbeknown to me. You are definitely going to fight this and your whole team will make the best choices for you to make sure that cancer’s butt is kicked and stays that way.
Let us know what your diagnosed stage is and keep posting. We’re with you.