M 20 year old. I've done sex with my boyfriend on 15 dec and he did'nt ejaculated inside me. Now its 7 dec and iI supposed to received my period on 2 dec and not yet received. I've sore breast from last week and cramps in my stomach from yesterday. These are the usual sign of my early periods but somewhere iI m worried that can iI be preganat. And if m then what should iI do because iI don't want to get pregnant

I am assuming that you did the sex on the 15th of November. Was there a condom? Even if he didn't ejaculate in you doesn't mean there wasn't enough sperm/semen in the precum from before he withdrew to impregnate you. There is enough to cause pregnancy. Withdrawl method isn't a good method of birth control.

It could be that you're period is late. I am not sure how regular you are but if you think you should have started on the 2nd then I am going to assume rather regular. You could get your period still if these are signs of you period starting.

What can you do at this point:
1). Wait for another week or so, the 16th or so, and take a home pregnancy test if you haven't gotten your period. The surest sign and symptom of pregnancy is a missed period.
2). Use that time to contemplate birth control. Finding a method that will be used and prevent these scares in the future.
3-a). If you're not pregnant then PARTY!! Then practice safe sex to prevent future pregnancy scares. Admit it, this uncertainty isn't fun.
3-b). You are pregnant. There are two or three things you can do here. If you CAN'T be pregnant then you'll need to abort the fetus. That is your choice I don't advise it or not advise it. It is an option. Two you can get married and have the child legitimately. You can have the child and give it up for adoption. It is up to you.

It isn't a fun place to be in and I don't envy you. Good luck.