Found A Lump

Hiya

i am 26 after giving birth to my daughter last year i went back onto the mini pill recently came off it about 3 weeks ago, a couple of months ago i had my 6 month postnatal check up mentioned that i felt like my left nipple looked a bit different she disagreed felt my breast for lumps said all is fine, nipple now doesn’t look any different but last week i felt a lump just above my nipple kind of hard to find it but when i do it’s round, hard and hard to move, see the gp today she can feel it she said she isn’t worried but it’s routine to get it checked she also said it’s moveable but to me it doesn’t really feel it, after the appointment i got an urgent suspected cancer appointment which has freaked me out i looked up the doctors notes she’s mentioned that it’s 2cm, hard, adhered to superficial tissue, that sounds worrying? could this lump be because of coming off the mini pill? why didn’t the previous doctor find this lump? sorry just would like so advise, ultrasound is booked for next week