Doctor says benign but not sure what it is

Let me start by telling I'm Dutch, so my English is not perfect, sorry!

A couple of days ago I went to see my gp because I felt a thickened string of tissue in my right breast (starting above my nipple and going straight op). He told me it didn't feel like cancer and not to worry but ordered a mammo for me in the hospital that afternoon. Mammo was absolute perfect on both breast but because I was so scared the assistent radiologist told me she woul find out if a radiologist could do an ultrasound too to ease my mind. 5 Minutes later I got the ultrasound and the radiologist asked me if I recently experienced any trauma to my breast or an inflammation because he could see some irregularities that looked like that. I told him that I didn't think so but that I just quit breastfeeding some months ago after breastfeeding over 5 years and that was the only breast that got a clogged duct every now and then. He didn't think that had anything to do with it and assured me he couldn't see a reason to take a biopsy right away and to see him again in 3 to 4 weeks so he could check again. The radiologist left the room and the assistent assured me that he would have taken a biopsy even if he had the slightest concern about what he saw and she told me that if I could it would be good to let it go for the next 4 weeks and not be scared.

My gp called me that afternoon to discuss the results and told me he was sure that it is benign and to not be scared.

But of course I'm scared to death. Because I still don't know exactly what's in my breast and I have to have my period in the upcoming days so my breast are swollen and painful and a constant reminder of the fact there's something "weird" in my breast.

I'm 39, no family history of breast cancer (or any cancer), non smoking, non drinking. But lost baby brother and have had problems with health anxiety ever since. Thanks for reading. I hope someone recognizes my situation and help me to have some more faith in my amazing doctors.