Aih, kalau line makin nampak each day tu actually is a good sign lah! Chemical pregnancy biasanya line akan fade away, but yours getting darker means HCG levels are rising, which points to proper pregnancy lah. Since your due period is 4/2 and you're already testing positive from 30/1, you're looking at early positive, repeat test dalam few days or check dengan doctor to confirm and rule out any complications, tapi honestly sounds like you're pregnant! A few of my mum friends had faint lines yang got darker, and all turned out to be healthy pregnancies, so fingers crossed for you!