Is My Girlfriend Pregnant Or Just Over Worried?

well about 3 weeks ago, my girlfriend and i who are both 16 (been together for 2 years) attempted at having sex for the second time, we used a condom but my penis didn't actually go into her vagina, it hit the rim of it once then after that we stopped. i did not ejaculate at all but i did pre ***. 2 days later i had checked and had seen that the condom was out of date by atleast 2 months. the condoms was not broken at all. ever since my girlfriend has had sore breasts, tiredness and her period was due today which she did not get. she took a test yesterday and it came back negative. before we attempted at having sex she had been stressing out alot with family issues and still has been since, we are getting really worried and considering were both still young we are to scared to tell anyone and we are not sure on what we can do at this stage other then see a doctor which is really difficult for us as we don't want our parents finding out.

could we just be over thinking this or what? please we need help ASAP