Second Opinion?

I'm 20 years old and recently found a lump in my right breast. Knowing breast cancer runs severely in my family I went to go have it checked out. I wasn't too worried initially as my younger sister had one in the past that completely when away and I'm still young. I made an appointment with my doctor and she didn't seemed worried at all. Said it feels like maybe 1 cm is probably nothing to worry about. She said I could go get an ultrasound if I felt like it was necessary.

Fast forward to the day of the ultrasound. The ultrasound technician took about 15-20, then called on the main specialist/doctor to look at the image and she took around the same amount of time. It felt like a long time but I've never experienced this before so I don't know. Turns out the tumor was bigger than originally thought. It was more like 5 cm and not 1cm.The specialist said that I should have a biopsy done sooner than later. So she did one that day on the spot. I was kinda concerned about her sense of urgency for the biopsy. She's took a biopsy as well as a mammogram. She said she's call in 48 hours with results.

After 5 days of waiting and me calling wondering where my results were I get a phone call, she tells me it's benign and nothing to worry about and to have a nice day before she hung up. I never saw any pictures or had the chance to ask any questions. Should I get a second opinion? I just thought I'd fell good about a benign result but I still feel uneasy. Sorry for the long post.