Contractions at 23 weeks

I am 23 weeks pregnant and I have been having contractions. I have went to the hospital twice in the past weekend for having them. I'm not dilated at all but I am having them and was given terbutaline shots to stop them. They don't have answers for me every time I go they say it's normal and give me the shot to stop them. They did swabs to see if I have an infection and if I was going into pre-term labor in the next two week which both came back negative. Have any mom's been though this before there was there actually something wrong or are they normal?