Yellow discharge. Is this normal?

Hi All, This is my first pregnancy through IVF(4th attempt) & I'm 14w5d currently. Throughout the first trimester it was smooth sailing but I started having yellow discharge as I entered the 13th week. It became more frequent so I decided to see a private gynae while waiting for my KKH 16th week appointment. Was prescribed Utrogestan and baby was doing fine on scan. Next day after the visit, yellow discharge turned brown and looked exactly like spotting. Lasted on one panty liner only. Contacted the private gynae and was told to monitor. Tested Negative for infections the following day. Was advised all these was a normal pregnancy physiological discharge and normal natural mechanism. Five days later brown discharge appeared again but lesser than the first. Also, lasted on one panty liner. Went to KKH urgent O&G: baby ok on scan & no blood discharge on speculum. Was discharged with "threatened miscarriage". Three days later(today) I had dark yellow discharge again. Anyone had the same experience with discharge for a full term pregnancy? Appreciate any insights. Note: all the yellow discharge had no pain or itch. Only slight smell.