Hi reading what u have posted it could very likely be that u are pregnant. the heartburn doesnt really kick in til u are a good couple of months preg as that is the uterus pressing on ur stomache causing heartburn. There can be other tell tale signs of pregnacy; nausea,tender breasts,tiredness,nipples will appear darker and u may need to wee more often. may i ask when u did ur test? if it was early on then it may have been a false negative & i would suggest doing another test or going to ur doctor to confirm whether or not u are preg. However if its confirmed u are not & ur periods are still irregular and concerning u I would definately talk to ur doc to find the reason for this. I hope this helpful x