Possible miscarriage?

So I'm supposed to be 7 weeks pregnant. After 2 ultrasounds in the last 2 weeks my doctor couldn't find the baby because of my tilted uterus. He sent me for bloodwork earlier this week to check my hcg levels. They called me yesterday saying that they went up but not as much as they should have. They scheduled me an ultrasound at the hospital next Friday because they have stronger equipment. They couldn't tell me what was wrong or why my levels weren't going up like they're suppose to. Well, out of curiosity last night I took a pregnancy test and it came out negative. I haven't had any cramping or bleeding or anything that a miscarriage is suppose to feel like. I never passed any tissue or anything. I need opinions on what could be going on. I'm not going to tell my doctor about the negative test. I'm going to wait for the hospital ultrasound and see what the result is on that. But I'm already assuming the worst and that at some point I miscarried and my heart is breaking right now. I can barely keep myself together at work.