Questionable positive test

So, I got two lines on a strip test 2 weeks ago on my birthday. Decided to test using a digital test and it was negative, took 4 more strip test and still two lines. My period was only 2 days long last month, and it is late again. Is it possible that I need a blood test or when you have pcos, it's hard for a digital test to pick up the hcg levels, please help as I am confused on what to do.