How accurate are ultrasound scans?

I found a lump in Jan and was seen 15 days later in breast clinic. They did a mammogram and ultrasound and said it was all ok.

I then requested a copy of the letter from the hospital. It does not fill me with confidence.. See below. 

So I went with 1 lump in the 1/2 o clock position if you are facing me or the 10/11 o’clock looking down. He first mentions the 8 o clock position ‍♀️ which is not why I went.. but goes on to say I have bilateral lumpy breasts - which I don’t believe is an actual diagnosis. He is noting fybrocystic changes and axillary tails and a ridge but no mention of any kind of follow up.

So I decided to pay for a private consultation last week. He started to say he didn’t believe there was anything to biopsy - he had a copy of the letter below. But examined me and backtracked a little saying he could see why I was concerned and that he’s overbook his Monday clinic and I’d get seen there for a needle biopsy. Now the thing I made extremely clear at this app was that I wanted scientific proof it was a benign lump.

So today I attended the clinic again and was given a 2nd ultrasound which they said looked fine and they did a fine needle biopsy and the results came back as inconclusive. He then told me to “watch and wait” and if it got any bigger to get in touch with GP. What I’m wondering now is why they didn’t offer a core biopsy?

What are other peoples experiences of this?

Thanks

referral from GP to hospital:

Dear Colleague
Ckground
I would be grateful for your urgent assessment of this 41 year old lady who noticed a
lump in her right breast this morning. No skin changes, no discharge and no previous
breast lumps. She is not on any contraception currently and her period was last week.
She was previously on the mini pill 5 years ago. She is known to have ulcerative colitis
and currently on Mesalazine. Both her mum and grandma had breast cancer in their
70s and 60s respectively. She is a non smoker.
On examination she had palpable firm irregular lump at 1-2 o'clock on the right breast
which was quite tender, and a palpable smaller lump in the axillary tail of left breast,
non tender. There was no axillary lymphadenopathy. No nipple discharge.
I cannot completely exclude malignancy.

Below is letter from clinic to my GP:

Thank you for referring T to the Breast Clinic where I saw her in my clinic today.
This young lady was worried about lumps, mainly in the right breast at the 8 o'clock
position. She tells me that she does not check herself regularly.
On clinical examination she has bilateral lumpy breasts. Both axillary tails have
fibrocystic change however in the area of concern at the 8 o'clock there was a small
ridge of breast tissue which felt like either a cyst or benign changes.
Her mammogram was reported as normal - M2 and her ultrasound reported benign
fibrocystic changes over the area of concern which we marked and did a targeted
ultrasound over.
This lady was reassured and discharged from the clinic back to your care.