Anxiety or Heart Issues?

Before I start I want to inform you that I do have severe anxiety and panic disorder. I'm also a 25 year old female. About 2 years ago I started experiencing these awful chest pains. It scared me so bad I went to the ER to get checked out. They did chest x rays, ekg, etc. All of those came back normal. So they sent me home and said to take asprin. The pains kept coming back. It was to the point where I couldn't leave the house. I quit my job and everything. Everyone told me it was just my anxiety. I finally set myself up with a PCP. Told him all the symptoms I was experiencing, convinced I was going to have a heart attack. He had me do another xray, a stress test, blood work, and wear a heart holter monitor for 72 hours. All of those once again where clear. So he put me on a low dose beta blocker and it's done wonders for me up until about 2 weeks ago. The chest pains, dizziness, heart palpitations, shortness of breath, left arm pain and tingling, etc all came back. I missed 4 days of work cause I couldn't leave the house. Again went to the ER a few days ago over this.... nothing was found... is it all anxiety and in my head? Or is there something wrong with my heart? It's ruining my life... I had all these tests done to show my heart is healthy but I can't help but think my dr missed something... thanks for reading.