Lump... thickening, now what?

A couple of months ago my husband noticed a “lump” I felt the area & said nope, feels normal. Then a month ago he again felt my breast & insisted it was not normal, that the lump was bigger. This time, it caught my attention I realized he was right. I went in for a physically breast exam and the dr referred me for a diagnostic mammo & us. They were considered “non cancerous”, but the radiologist could also feel the thickened area. With no explanation or closure I was referred to a breast specialist. I’ll go in two weeks.

My question Right now is probably super simple, but I can’t seem to find the answer. I know many of you are knowledgeable & I would love your help.

My breast are very dense. However, this area of thickening is new & seems to be getting larger. My question is can glandular tissue or thickened tissue just appear? I asked about common non cancerous causes & all the dr said was that in the us it looked normal. He could see nothing “today” I am young- 33, healthy, only risk factors are family history & dense breast tissue. I know that 80% turn out to be nothing. Do I just wait to see if it gets even larger?! I just don’t know. Thanks for any help!