Former cancer patient and breast lumps

Hi everyone. I am 29 years old and this is the first time in my life I have had any breast worries. It’s been a while now that I have noticed a sizeable-the size of a macadamia nut-lump almost directly underneath my left nipple and a smaller one close to the first one but more to the outer side of my breast. I have very small breasts so I can easily feel them. They are both hard, firm, and round, and might be connected to each other but I cannot tell. No nipple discharge, but I have noticed that this month, just before my period, the lump under my nipple feels a bit larger and my nipple looks like it’s not as pronounced as it used to be and is slightly facing upwards-I guess due to the pressure from the lump. The area is sensitive, it can get uncomfortable/slightly painful/burn sometimes when I wear a tight bra, if I squeeze the area or if I lay down on my back or side. It’s always more “sensitive” just before and during my period. 

Due to COVID, my doctor is only taking emergencies at the moment-I called for an appointment but they told me that the situation is not urgent and I should wait a bit longer so I can get a referral to a gynecologist. However as on the title of my post I have had cancer during my childhood (Wilms’ tumor/neuroblastoma) that took years to clear up and I am really, really afraid that this is cancer and I will end up facing the same situation again, 20 years later. I am getting extremely stressed and I know it’s not mentally the healthiest thing to do but I am trying to find out if there are any other possibilities than cancer considering my symptoms? 

Absolutely insist on a referral to the breast clinic!! Lumps should never be ignored regardless of age.  The good news is that Most referrals to the breast clinic turn out to be benign and that would be the greatest outcome but you just never know and it’s not up to the surgery to decide this, that’s what the professionals in the field are for and that’s why breast clinics exist.
So call back the surgery Monday , get a GP To call back if they won’t give you an appointment and insist on a referral! 
Good Luck , I’m sure it will all be fine but let us know how you get on xxx