so I'm like superrr late

Lilith
Hey ladies, trying to get opinions or thoughts on this because I am COMPLETELY stumped. I am currently 17 days late for my period (I'm usually never late!) 
My cycle days are typically 35 days long and I'm on day 50 something (I lost count!). I'm nauseated (mostly at night?), some weird clear stuff is coming out of my nipple (tmi!), and I'm bloated as HELL
The only time I was ever this late was when I was pregnant with my first born. But I've taken MULTIPLE pregnancy tests, all negative but one looked like it had a plus after a while. What do you think? I have a doctors appointment Friday to get a blood test, but what do you think? Is there a possibility or am I just stressing myself out and causing myself to miss my cycle?