Scared and confused

Please hear me out and keep a opened mind . 
About 3 weeks ago i did it with my bf but it didnt last very long . It was just awkward and we kept stopping so we just gave up in the whole idea . He did not finish in me or at all so he claims . I finally got my period a few days ago . But i have been feeling a little nauseous like the feeling is there but nothing happens . I gained back a few pounds i barley lost . Although i have been under tremendous stress these past few days .  Should i be worried ? I am 17 going to be 18 in a few months . Talking to my parents is not a option . I really regret what i did and dont know what to do.