What's causing my high blood pressure?

here's the story. i had a medical check up about a month ago and my blood pressure was 130/90. This wasn't the first time it reached that high, in fact it had been like that for past check-ups. Since then i bought my own aneroid sphygmomanometer and did regular checking of my BP during mornings and nights. It was still 130/90. Then it got higher to 140/90, and it lasted for days, but i found out that it was due to whitecoat hypertension. Then over the past weeks i've overcomed that tension in measuring my BP , and it got back to 130/90. ( but it still sometimes reaches 140/90 when i'm nervous.). Rarely, it goes back to normal or near normal like 120/90 or 120/80, but the consistent BP reading is stil 130/80 - 130/90. My doctor said it was due to psychological factors and stress, caused by me overthinking and depressing on the matter, but i'm not convinced. I had a blood test with the doctor and the results were fine. My cholesterol levels and triglycerides were all normal, everything was normal( unlike before when my cholesterol levels were above normal range.) Now i am maintaining a consistent exercise regimen and proper diet and i have been doing this for about a month now but my BP is still around 130/90. my question is, what the hell is causing the increase in my blood pressure? i kept asking this question to my doctor but she keeps answering back the same thing about psychological factors, that it's all in my mind. Note that i also feel palpitations sometimes, strong heartbeats that happen occasionally. Like, my heart beats strong for 1 beat and then it goes back to normal. I feel like these palpitations has got something to do with my high blood pressure; i've already told this to my doctor but she keeps ignoring it. I need a second opinion from a professional. Also note that after having graduated from college, i have been sleeping and waking very late for about 5 months straight while i was still unemployed.(like sleeping 5 am and waking up 2pm the next day) ; could this be the main reason for my high blood pressure? However i have already fixed my sleeping and waking schedule now and it's back to regular sleeping and waking hours since i am already employed. I need professional opinion. Thanks guys.