Negative test, but 18 days late...?!

This is so frustrating. TTC is frustrating. I am 18 days late on my estimated AF and STILL no positive test - all the symptoms though!

There's the bloat, the extra cervical mucus, the sore breasts, the gas, eating SO MUCH, exhausted, and of course the late period. I feel like I see a faint line and retest 48 hours later and no improvement. This would be my 4th pregnancy so I'm not necessarily new to the whole pregnancy thing, but I am THIS close to contacting my OB... is that appropriate?