Hi, Thanks for your query. From the information you have provided , your periods have delayed by 12 days and you had irregular bleeding few days earlier. Not all pregnancies show up in urine tests & this can be one reason why your hpt test was negative. Also very early pregnancy where the HCG hormone concentrations have not reached the particular level, the upt test can be negative. Since its been a week after you have had a negative hpt, it makes sense to repeat the test now. The subserosal fibroid has nothing to do with this delay. Regularity of your cycles is usually affected in hormonal imbalance or ovarian problems. With fibroids depending on the number, size, location the symptoms can be pain, difficulty in passing urine , difficulty in conceiving, increased bleeding, inter menstrual bleeding, post coital bleeding. The 5 cm subserosal myoma that you have is unlikely to cause this. If it has a narrow stalk then it can twist and cause pain( what we call as torsion). If thats not the case, we can wait and watch. As of now, If pregnancy test is negative , maintain a menstrual calendar for next 3 months. If cycles become normal, all that you will need is annual scan for your fibroid. If cycles continue to be irregular, meet your gynaecologist who will ask for tests to find out whats wrong. Best wishes. Take care.