GP can't feel lumps in vagina

I am 35 years old, went to my GP after finding lumps in my vagina. There are 2 hard lumps, around pea size, which I can feel thru the very top part of my vagina, behind the cervix, but are not actually inside the vag, if that makes sense. I found them when I was feeling for my IUD string 2 months ago, not sure how long they have been there as its not an area I usually poke about!

I have also been getting severe lower left stabbing pains and spotting a week before my period. My period is 6 days, stops for 2 and comes back on day 9 with extreme pain. GP said it was ovulation pain.

Anyway GP examined me, could see nothing, and feel nothing. But she said she couldn't feel behind the cervix as her fingers were too short. 

She said nothing to worry about, the only thing it could be is pollyps which are harmless. And yet I'm not reassured especially as she couldn't feel the lumps which I can very clearly feel. My mum had ovarian cancer which was very advanced by the time they found it. I don't want to be taken from my family so young :(

I am thinking of paying for an ultrasound privately. Does this sound overly paranoid? Would lumps show up on there?