plan B and pregnancy

So I got my period on April 15,2017. I have sex in the April 24 and I had sex twice on this week. The first time was Monday and we only used condom as our prtotection and the condom didn't broke and he said that he didn't cum since I got tired fasts. The second time was on a Thursday and the condom broke, but my boyfriend claims to have pulled out as soon as he felt that he was going to ejaculate. I took Plan B a day after having sex.  So exactly two weeks later I went to the doctor and they did me a urine pregnancy test and something weird happen. They practice 5 tests and it showed one line and the other one was wavy ish and blurry. But then they did another one and it was negative. The doctors told nothing like that had ever happened. Should I be worried or not?