Late period, strange symptoms and superdrug tests!

[Joann29]

Hi, I'm fairly new here! Myself and my partner have been TTC for 15 months now. I've been tracking my cycle for over a year and my cycle is usually 26 days, never any later than day 27. Today will be day 28 of my cycle and still no AF. I've had an upset stomach for about two weeks now and pain in my stomach, sometimes it feels like period cramps, other times it feel like a stitch or my abdomen muscles feel sore. I've had heart palpitations for around 4 days now and happen completely out of the blue. I've been exhausted and lost my appetite a little. I'm still eating to keep my energy up as I work long hours but not as much as I usually eat. I've been getting a lot of headaches and my breasts are tender. I took a super drug pregnancy test today but it was a BFN. I know the symptoms aren't exactly tell tale signs of pregnancy but has anyone else ever experienced anything similar? I've heard that super drug tests are supposed to be good, I'm trying to wait to test again! This would be my first pregnancy and I'm just dying to see that BFP after trying for so long! Any advice would be greatly appreciated!