Lump won't go away, getting nervous. Input?

Hi all, first time posting here. I've read the stickied post about guidelines for starting a new thread, and I've also checked out the links provided (like benign causes for breast lumps). With that said, I'm currently going through my second scare over the same lump I had looked at a year ago, and I would really appreciate some input from an actual person at this point.

Last year around July or so, I noticed a small, pea or marble-sized lump on my left armpit while taking a shower (right over the axillary tail). It was admittedly a bit hard to find - I had to run my hand over it more than once just to make sure I was really feeling something there. I didn't freak out initially, and thought I'd wait to see if it disappeared on its own. By the time September rolled around and the lump still had not cleared up, I was noticeably anxious about it and mentioned it to my then-primary. He was unable to feel the lump without me showing him (using my own hand) exactly where it was. He didn't seem at all concerned and determined that it was a swollen lymph node. I was prescribed antibiotics and told that the lump would either shrink or disappear. It turned out that I would not be able to take the antibiotics without vomiting, and the lump did not go away (since this experience, I've been prescribed strong antibiotics for unrelated infections like UTI's, and the lump still has not diminished in size).

I went to Planned Parenthood for a second opinion. The doctor I was seen by there also had some slight difficulty finding the lump at first, but was definitely able to determine that she felt something. She told me that it "didn't feel like anything to be worried about," but that I should still have it evaluated further. I was referred to a cancer center for a mammogram, but plans to make that appointment fell through as I was hospitalized for low hemoglobin (separate issue). After my blood transfusion was over with, I made it a point to bring up the lump to my doctor and nurses at the hospital while I was still there. The daytime doctor couldn't feel it, but one of the nurses and a physician's assistant was able to feel the lump after prodding around a little. A week after I was discharged, I went to a hematologist/oncologist to address primarily the anemia, and then the lump afterward. Of course my hematologist couldn't find the lump, but he did order an ultrasound and a mammogram for my peace of mind. The results of both came back normal, and I was told in a written report of the findings that I did not have dense breast tissue.

Fast forward to now, a year after I first discovered the lump in the shower. It feels a little larger to me - about the size of a gum ball. It isn't difficult to find anymore, and I can see it protruding a little when I pull the skin over it downward (and gently, at that. I don't have to seriously stretch my skin to see it or anything). I had it looked at by my current primary doctor, and she was able to feel it right away without having to digging around. She did comment that it seemed to move, which I took as a positive. I'm supposed to have an additional ultrasound done this next week on Thursday, August 15.

Things that have me relatively concerned at this point are as follows:

- It has been a year and the lump has not gone away.

- I'm not entirely certain that the lump has actually increased in size, but it went from being difficult to find by myself and my doctors to being easily felt on the first try.

- Over the span of the last year at least, I have experienced things like intense itching of my left nipple (it went away after about a week and a half) and occasional aching/shooting/stinging pain in my left breast. Some slight itching of my nipple was felt again on Friday (08/09/2019). While I've always heard that breast cancer is not painful, I've read enough from others here to learn that a fair amount of women do experience pain. These symptoms are felt on the left side, which happens to be the side the lump is on.

- I saw a flyer at my gyno's office a couple years ago that stated having a first degree relative with ovarian or breast cancer puts you at higher risk for both. I've not had any genetic testing done, but my maternal grandmother was diagnosed with ovarian cancer at 65. She did eventually pass away from it. I will be honest and say that I don't know how that relates to the possibility of me having breast cancer now.

For anyone that's stuck around long enough to read this far, I suppose these are my questions: Just under a year ago, my ultrasound and mammogram came back negative. Again, the lump is still there and I feel it may have increased a little in size. Am I right to be a squeaky wheel about this? I've not had it biopsied. Would it be overkill for me to push for a biopsy, or at least removal of the lump to be sure? I've heard of false normal ultrasounds and mammos with dense breast tissue, but what could possibly be the reason for my lump to be missed by both of those things if dense breast tissue is not an issue for me? Has anyone here had a normal ultrasound or mammogram, only to find out later that your lump(s) or symptoms were serious after all? As the title states, I'm really concerned that I'll be looked at as someone digging for problems. That maybe I won't be taken seriously after I've already been given normal test results. I tend to be a bit of worrier anyway, but I can't help but feel like I shouldn't let this go until I know for sure.

To anyone that reads, thank you so much for your time!