Can ovarian cancer be missed in a transvaginal ultrasound?

Hi all this is my first post, 

I will try and keep it short and to the point, but basically I am worried as on the 7/6/19 I suddenly become severly bloated, which is persistent ( it don't come and go)

The only time this has ever happened to me in the past is when I was pregnant, so I thought I must be pregnant as this come a  few days after ovulation, 

I have had 3 periods since, negative pregnancy tests and negative hgc blood tests so there is no baby. 

I also have

pelvic pain

Hot flushes 

Exhausted

Feeling full

A lot of clear discharge ( not very offensive but smells different)

When my period does come it stops and starts 

My GP sent me for a Transvaginal ultrasound of the pelvis, which come back normal. 

During the ultrasound the sonographer was very rude and I felt discriminated against ( by the way she spoke to me and didn't listen) , she literally shoved the probe in and wiggled it abit and sent me away. I left  in tears and not feeling confident she even checked me properly.

I told this to my Gp and he just said well its come back normal, I told him I'm in pain and my stomach as you can see it's huge, I look pregnant! It's  now been over 2 months I have had this persistent bloating ( it's not gone down at all) I even stopped eating and just had water to see if it went down and its not! He just prescribed me antibiotics and said it will help with the pain.

I have asked my gp for blood test but he said no, and was very stubborn about it. He won't refeer me to a specialist, when I said I think I have maybe ovarian cancer he said no you don't as scan is normal and now won't take me serious. 

I dont feel confident about the scan, and I know my body and this is not normal for me, but I feel like I'm talking  to a brick wall. 

I can feel a small lump on my left lower stomach too and the pain and bloating getting worse 

Is it possible for a ultrasound to miss a cyst or mass? and how can I get refereed to a specialist or atleast a  blood test?

I feel a anxious mess, I worked for the NHS for 10 years and now I need help I cannot even get a blood test I feel so frustrated. I know I'm not the only one this happens to, I'm Just venting as I been so anxious about it. This is the first time I have tried to get referred for a illness,because I feel like it must be serious.