What Are The Early Signs And Symptoms Of Pregnancy?

Sir my problem is i have fore played with my gf on 31st of march in this foreplay i have also touched my penis on her vagina but i have not inserted it in her , next month this she is not having her periods so we have decided to do a prega news pregnancy test & test came negative with a single line that meant she s not pregnant & finally she gets her period 18-20 days late but the periods are normal like she always have. but since that period she hadn t get her period. & today is 27 july that means she missed 2 periods is there any chance of pregnancy. if yes then what i should do to avoid it should i do pregnancy test again to confirm it ?? & the biggest thing which i want to tell you is she thinks a lot, take a lot of load on her mind,take a lot of tension, always worried about everything i am telling you this b coz i have read several times that tension is the biggest factor which effects Menstrual Period plz suggest me what should i do