Experiencing false symptoms. Condition?

When i suspected I might be pregnant, out of fear I did multiple pregnancy tests over the last 2.5 months, which were all negative. I did around 10-15 pregnancy tests, 3 blood b hcg tests and even went for ultrasound twice. I didnt even miss my periods, I am getting periods regularly. So technically I should not be pregnant, even my gynae told me so. But surprisingly, I am experiencing pregnancy symptoms.. Like increased stomach size, presence of linea nigra line which appears on stomach mostly in pregnancy, sometimes I feel flutters and heaviness in my stomach, which was not there before. Even my boyfriend abadoned me, which is furthur increasing my anxiety. This fear of pregnancy is constantly there in my mind and am unable to live my life due to stress. Has the fear in mind tricked my body into believing that I am pregnant? Am I suffering from pseudocyeis (false pregnancy) ? How common or rare is this condition? Please tell me how can I overcome.