TTC with symptoms but always NEG:(

Me and my partner have half-heartedly TTC (if it happens it happens, if not, not to stress). But I feel like I take this on way too much and over react when I have signs that could be pregnancy. For example, in the past I've had like twinges and cramps and took a test too eagerly and it was neg.  however, nearly 3 weeks ago we had unprotected sex and after about 10ish days (maybe more) I noticed I was bleeding, really really lightly and it only lasted a day. The only time I get this is just before AF comes, but I'd just come off a week previously. Then, I started noticing slight twinges and cramps in lower tummy (uterus area) - only light ones and different from AF, then I notice my lower tummy feels harder and very full. Next, I was cooking and the thought of eating the food made me feel so sick, and eating some foods (cornbeef!!!!) made me feel sick aswell! I've not been physically sick though. And then I get heartburn when I have never ever had that, then really sore/sensitive nipples and again I never get that! after my shower, I couldn't stand having my towel wrapped around my body, it hurt so bad. I took a test on 25.7.15 which turned out neg, so I thought I'd wait another few days and took another (28.7.15) and again negative. I'm so disappointed with these results, I really thought I was preg. I feel like I want it so much that I'll convince myself that I have signs and symptoms, does anyone else feel like this?! It's so horrible