Verrry stupid idea but I can't get it out of my head!

My nan was given 2 years to live in 2014 due to having terminal cancer and so far she's battling all the odds and if you met her you wouldn't even know!

Im 20 and my boyfriend is 23 and have been together for a long time, we had a miscarriage back in January

I've always wanted a child young and now my nan who always said she'd 'kill me' if I got pregnant young has started hinting at wanting a grandchild and there's nothing more I want in life than to have my wonderful nan meet my baby before she passes.

Im so tempted to bring up TTC with my boyfriend and its not only for my nan but for me too, I have a good job and so does he, financially stable etc but I'm not sure how to go about it

Having a child in my early 20's and for my nan to meet a great grandchild means so much to me and we're already on 'borrowed time' that I've even considered ending things with my amazing boyfriend to find someone else who would be willing to have a child at this age with me

I don't know what to do😔 I don't want to leave it too late😢