Hello and welcome to EmpowHer,
I'd like to explain why you are not pregnant from these events. First of all, pre-ejaculate does not always contain sperm. When it does, the sperm can be damaged very easily. If there is no penetration, it is very unlikely the sperm will enter the vagina at all.
Secondly, after you took emergency contraception you started to have all the usual side effects: bleeding a few days later, nausea, cramping tender breasts etc. Taking EC correctly will effectively prevent pregnancy.
The negative pregnancy tests are a further indication that you are not pregnant.
I suggest you try to reduce your stress and see a doctor is you continue to have digestive issues.
No need to worry about pregnancy.