Terrified waiting for ultrasound

Hello. I hope it's okay for me to post here. I have not been diagnosed and am waiting to get an ultrasound in 2 days. I am turning 25 in 2 weeks.

My story- I began feeling tingle and pain my left shoulder that radiated down my arm for weeks. It has greatly affected my sleep. Everyday my fingertips are tingly and my shoulder blade pain keeps me up.

3 days ago, my left breast began feeling very swollen and painful, localized to the left side. I touched it and felt the lump. This lump is familiar, its been there for a long time and I never got it checked out because I wasn't aware that young women could get breast cancer. Feeling stupid and naive about that assumption. My lump is large and moves around when I push it. It's hard to tell the shape or edge texture because my breasts are very lumpy and it's difficult to differentiate. My left breast is also so swollen, it's hard to get a feel for the whole lump. My nipple on this breast is also inverted

I have had slight pain and tiny lump in left armpit that I have also ignored for probably a year.

It has been 3 days of constant burning pain in my left breast. The muscle near my shoulder blade has been extremely painful the past couple of weeks and as I write this, the pain is keeping me awake.

I am so scared. My family is scared. I work full time at a job I love, I just moved in with my boyfriend, and life was going really well until the pain started.

Everything I've read online with my symptoms leads to worst case scenario. Not knowing and living in pain is aggonizing.

Has anyone had a similar situation prior to diagnosis?

Thank you for reading