2 missed periods..help!

I missed my first period June 7-10 and I got a couple faint positives. I spotted a little bit off and on 2 days but it wasn't heavy like a period. My last positive was June 29th and ever since then I've been getting negatives. But my next period is due this week and I don't think I'm gonna have it. Should I be worried I might still be pregnant or something is wrong with me?!