Is eGFR of 75 normal for a 49 year old female?

I am a 49 year old caucasian female. I have ovarian cysts, high cholesterol, fatty liver (I don't drink alcohol), shortness of breath for the last year or so, my back is always itchy, and about two years ago I started having urinary incontinence, urgency, and frequency. About a year and a half ago I was in the emergency room for chest pains which is when they discovered I had a cyst on my ovary. The chest pain was diagnosed as musculoskeletal. I was released with instructions to follow up with an ob/gyn to evaluate the cyst for malignancy. My lab work at the hospital showed that my cholesterol was very high, I had high globulin, low potassium and sodium, and low mpv. My eGFR was 84. The hospital never mentioned the abnormal values and I was unaware of them , but I took a copy of my records when I went to get established at a practice that had ob/gyn and primary care a week after my release. They never said anything about my abnormal test results either. My cholesterol continued to increase for the next year because I didn't know it was high. So I had bloodwork done about 6 months ago and my cholesterol was much higher and I requested medicine for it (simvastatin). My eGFR is now 75. The recent lab results also showed that I had low BUN. I bought some urinalysis reagent strips online and have taken about 30 tests over the last couple months,all of which showed low positive for bilirubin. I told my doctor but he just blew me off and said that those strips sold online are unreliable. He didn't do an in-house urinalysis either. He also said that my eGFR was normal. But from what I have learned online, an eGFR of 75 is not normal for a 45 year old woman and indicates decreased renal function. So I would like to know if my eGFR really is normal and also why the 9 point decrease in a year's time. Is that also normal? I am still having problems with incontinence but my doctor said it's just age related. Can you please explain my eGFR values and if they indicate renal dysfunction or not? Thank you for your time.