I have an enlarged prostate.......?

My doctor said that my prostate is large than normal. I had my blood tested for PSA ( prostate specific antigen) and showed a 6.5 ng/ml. The normal reading should be 4.0 ng/ml and below. I took antibiotic for 2 weeks to determine if the cause is bacteria or just inflammation. My blood was again tested and showed a reading of 5.5ng/ml. It goes down but still not normal. Again I took antibiotic for another 2 weeks and had my blood tested again and showed a reading of 5.75 ng/ml. I was tested for DRE ( digital rectal examination) and no lump was found. He then advised that to determine if the cause is just simple enlarged prostate and not cancerous, I will have to undergo biopsy.

I checked the internet and found that some patient with similar problem as mine had infections and had a hard time urinating. What can you say? Should I undergo biopsy? Please to those who had previous experience. By the way I'm 59 yrs old.