Noone will give me a ultrasound :-(?

iam almost 2 months late for my period i feel like im pregnant having the backaches,bloating,increased appetite,frequent urination,tiredness,nauseau,swollen , im even producing freaking colostrum .. if iam really pregnant iam now 7 weeks .. my urine test keep coming out negative and a blood test was negative a week or two ago so the docters want give me a ultrasound they keep saying maybe its a hormonal trigger but i heard those are only comin in woman in there 40-50 that are having menopause .. iam only 18 im so frustrated so is my boyfriend we just want to know do we have a little seed growing inside me or not .... what might be going on what can i do to have a ultrasound performed???