Persistent Shortness of Breath

Hey guys, I'm new here. I'm a seventeen-year-old female who's generally very healthy. However, about two months ago, I started feeling short of breath and my heart was beating really fast, and the  shortness of breath was so bad that I couldn't sleep that night. I went to the doctor the next day and she diagnosed me with bronchitis and gave me some antibiotics and an inhaler, due to my severe allergies. I have never ever had breathing problems before a couple months ago, not even when exercising. So I take the medicine, but it's not making me feel any better and neither are the inhalers. I'm having persistent shortness of breath; I still feel like I cannot breathe normally, difficulty taking deep breaths, and the feeling that I'm always not getting enough air. It got a little better about 2 weeks later and I thought I was getting better, but I'd still have times when I felt short of breath and dizzy. My parents and doctor both said it could be attributed to anxiety, since I get nervous quite easily and I'm worried frequently, but does anxiety cause chronic shortness of breath? I thought it would only come in attacks. But anyways, my parents decided to send me to the pyschologist to treat my anxiety but it hasn't helped yet. About one month after the symptoms started, I went to camp for 3 weeks to see if my symptoms would go away if I was in a care-free atmosphere and I wouldn't constantly worry about me being sick. Well, the camp was fun, and I did feel fine at some points, but then in others, especially out in the heat, I felt like I couldn't breathe. It's not dehydration or anything heat-related though, because I drank plenty of water, and when I'm indoors I still feel shortness of breath and extremely uncomfortable. At this time, other symptoms developed too. My stomach was tight and constantly bloated, and I felt more chest pressure. I'm not sure if those two are related, but i feel pressure right below my ribs. After coming home from camp, I stayed home and I gradually began to feel worse. Some times are okay, but I feel like I can never breathe normally and I also think about my breathing too much. The chest tightness continued and so did the stomach/thorax area tightness. I went to the pulmonologist and allergist, the allergist telling me I have slight asthma, but the medications I was on, singular, allegra, and inhalers did not really make me feel any better. The pulmonologist and my primary care pediatrician both said that there wasn't anything big wrong with me, and that they were just "growing pains." Is this constant shortness of breath just a growing pain? So then, I continued feeling worse so I went to a different doctor and she did an echocardigram on me and a chest x-ray, both came out clear. My parents also believe that there is nothing wrong with me, and that it is just my anxiety. They told me to go out and have fun, but I have tried those things and my symptoms are always present. In the past several days, I've been feeling worse. I began having more muscle tightness and muscle weakness and dizziness, like I was going to pass out. I'm going in for a blood test tomorrow to check if I could have any other problems, but I'm getting really worried. I really cannot live like this anymore, it's ruining my daily life. On top of that, I'm going to be a high school senior and I need to do college apps soon as well as enjoy my senior year, which I cannot with these symptoms. I desperately want to know what is wrong with me. I started feeling like my head was very heavy today and yesterday my family and I were going to watch fireworks, but I couldn't go because it was hard for me to breathe and I felt like I was going to pass out. Is nothing really wrong with me and it's all in my head? I really don't know, but this is really frightening. I don't have much of an appetite these days and I'm really worried I would have something outrageous like a degenerative muscle disorder(if nothing is wrong with my heart/lungs, could it be my diaphragm?) or a brain tumor. Are these possible? If I were to see any doctor, what kind would it be? My breathing does not get worse with exercise. Any help is greatly appreciated; I just don't know what to do anymore.