Pregnancy test. With exact solution plz.

Hello sir/ ma'am, I had a sex with my girlfriend on Jan 28th..she had her period in Jan between 15-20..after having sex got her period in Feb 1st or 2nd week..and while having sex we didn't used any safety..but I was consious enough that my sperm didn't went in her..but now she is not getting her periods since 2months (March, April) and now May has started..till now no period and she had a weight loss of 4kgs..ryt now she is 46kgs and sometimes she feels body pains..legs pain..back pain.. sometimes she get severe stomach ache..and she is saying that her breasts size have increased  she feels pain sometimes and we are afraid that she might be pregnant..as I know she can't be pregnant bcz..my sperm didn't went in her..I ejaculated it out of her..then how she could be a pregnant..can u help us with exact solution plz..and wat medicine to be taken to avoid pregnancy as we r not married so we can't keep that pregnancy..plz help us.. thanking you..