Confusing pregnancies to miscarriage

Allie
Hey there guys I'm 21 married with a loving husband, we have been ttc for a year now.. We lost a pregnancy on Christmas last year, I was 3 months and didn't find out we were pregers til the week before we lost it from an er visit and ultrasound.. I have had only one other miscarriage and I was 19 during that one.. So my thing is pregnancy tests (urine and/or blood work) neither will show results of a pregnancy. I'm just wondering if anyone else has this problem. Please let me know.. Drs think I'm crazy and even when I tell them I have symptoms of pregnancy, being a military wife they won't schedule me on obgyn apt until I have a blood work positive, this caused some what of my miscarriage last year, I was misdiagnosed with a thyroid problem instead of them realizing I was pregnant last year.. Well I'm having the same thing happen again, blood work came back -1 says the Dr and he won't do an ultrasound to check other wise.. I usually have heaver periods (since i started at 14) but lately I've had very light ones like I did with my previous pregnancies. Please help if you can. Thanks so much !