About 6 weeks LMP, neg preg test?

So my cycle is 28/30 days. It's been 40 days since my LMP though (almost 6 weeks). I've been "ually active" using pullout method a few times, and then a condom other times. I took a few pregnancy test (new choice dollar tree) and they came out negative, including one I took this morning. I've been reading on message boards about some women not testing positive until like week 6 or 7. Is there a good chance I could still be pregnant? I'm hungry ALL the time it's out of control, even things I don't like that much! Also I had tiny twinges of cramping last week, no bleeding at all tho or spotting, bloating in my abdomen (never bloated there, usually lower abdomen), breaking out BAD, cravings for sweets, and nausea but no acctual vomiting and sometimes lower back aches, lastly grew! (eep). So from all this information, is there a good chance that I could be pregnant, just have to wait longer than normal to test positive? Thanks any advice helps! Please no lectures on , thank you!