so friggin confused

So I am 19dpo, 6 days late on AF. I

have taken pt, negatives. I'm sure I am one of those that produce low HCG until weeks after. I had Brown spotting, lasting 2-3 days when I was 12-14 dpo. I have been TTC my second child. I feel bloated, intermittent nausea,mild, and more tired than usual. what are your opinions or experiences with similar situations?!? Should I assume and start acting (no caffeine, alcohol,nicotine,etc) like I'm Prego and schedule for blood work next week?!? I don't want to get too excited just to find out it's not that. Help please.