Spotting instead of period????

Hi guys,

I'm worrying a lot at the moment and I wanted to hear some advice from you.

I've been back on the pill for 2 months, this would have been my 2nd period after being on the pill.

But I stopped taking my pill on Monday, it's now Thursday and I haven't started bleeding. All I'm getting is a light brown, mucusy discharge. No cramps.

I was also experiencing extremely sore and tender breast over the last week and a half, they've grown a cup size in that time.

Could I be pregnant? I'm only 18 and I'm getting really worried...

Please help:(

Thank you