U.K. Mams and screening for Down's syndrome and spina bifida

Emma • First baby due 15th Feb 17 Baby BOY 💙
Hi ladies 
Went for my 12 weeks scan where I was also getting the screening done for spina bifida and Down's syndrome 
Unfortunately they weren't able to do those test as I have a tilted womb and they couldn't get the measurements 
So they said they will book me in for a blood test at 16 weeks 
I know they can only pick things up in the blood at 16 weeks but this seems crazy late for them test 
I feel very distressed over the wait .
They did say I'm not high risk as I'm only 25 and no one in either of our family's have had those . 
But I feel like I'm going crazy.
Anyone got any advice