Twilight.. pregnant or period?

Good afternoon,

Since May I’ve stopped taking the pill, and since this month we’ve been seriously trying to get pregnant.

Because I assume it might take a little while, I’m not too worried about whether I am or am not pregnant, but the symptoms I’ve been having lately are making me a bit nervous.
Maybe you guys can help me out a bit, because Dr. Google isn’t making me any wiser.

My last period was from September 16 to 21. It was 2 days earlier than expected and very sudden (no cramps etc., which I normally get a day before, but I did have the tender, sore breasts, which I usually get 2 weeks before my period starts and are often gone by the first day of menstruation).
I have a regular cycle, and I expect my next period on October 17.
I don’t know exactly when I ovulated, because I don’t really track it. My husband and I just have fun when we feel like it, not because it “has to” be done.

Now, for the past week and a half I’ve had more discharge (from slimy to white chunks and everything in between). My breasts are firm and sensitive, but I’ve had that since I stopped the pill; it’s just been longer than usual this time. I’m getting waves of nausea (especially in the morning and evening), and despite taking antacids, I regularly get heartburn.
Also, I’ve been tired and hangry for a week now.
But here’s what’s making me nervous:
Last night I got stabbing pains in my belly and groin. It went away after a while but came back later. I also lost some light pink mucus last night.
This morning I was nauseous again, and when I was briefly awake I got another stab in my belly, like I’m about to get my period. But that would be 3/4 days too early.
Also, I’m having lower back pain and I’m really tired again.
When I just went to the toilet, I noticed I have light bleeding.
Could it be that I’m pregnant, or is my period coming too early?

Sorry for the long story
Thanks in advance for your replies.