New, saying hello, feeling scared

Hi there, I've just received my diagnosis a week ago. It's been such a long long week. I'm 44 with two boys, 7 and 4. I've had fibroadenomas and generally dense lumpy boobs all my adult life, which made checking them tricky but also meant I regularly referred myself to further investigations, and occasionally biopsies. All would come back normal until this last one. 

Mine was described as an indeterminate lump and everyone thought it's most likely benign, but via the 8 biopsies it turned out to be ER 7, PR 4 and HER2 negative (or low, they didn't specify). I was told grade 2, and they didn't pick up anything in the lymph modes on the ultrasound. The lump is thought to be about 25cm (although the mammogram said something about 35-40cm distribution of micro calcifications? Also my letter said 20% distribution or something I didn't understand. I have my MRI next week. 

I've been holding it together as much as I can, and letting my friends and colleagues know. I've just had to have a big ol' handover of my workstreams at work . My kids don't know yet as my partner wants to wait until we know more about the treatment ahead. It's hard acting normal in front of them. 

I suppose the reasons I decided to post are that - since the diagnosis my body is experiencing all sorts of concerning aches and pains in my shoulder, shoulder blade and in my boob as well, and occasional head pangs. Also that I feel so incredibly isolated and struggling to find other under 50s to talk to. A lot of stories I read have mamas with adult children and I get upset thinking mine are still so young. Perhaps connecting here might help me feel less alone...

Ps I've signed up for Someone Like Me and been to my local Macmillan horizon centre etc.