I usually have irregular periods. They sometimes come every month, and sometimes a/f doesn't come but every other month. I have never gone three months without a/f. I took 4 pregnant. Tests. All urine home pregnancy tests. They all came out negative. I am wondering if I take a blood test, can the results say otherwise? Or does it not matter what kind of tests I take? Please someone help! I am 23 and never been pregnant.

I think it's time to contact your doctor for a blood test, especially since your period is not regular.
You very well could have just missed a month then gotten pregnant the next month and the hormones haven't built up in your system.
A blood test or ultrasound can rule out pregnancy.
Good Luck

Yes you need to go see your docter and just because the test said no dose not main that the docter will say no blood test is the best way to go it is 95 % right good luck