Most will experience symptoms below 15 nmol, all but one of your blood tests would have scored you a TRT protocol if you were in the USA. You issue once you start TRT is going to be your super low SHBG, SHBG is the foundation for activating and regulating sex hormones. Often when a guy starts TRT their SHBG will decrease a little, yours is already really low. Your other issue is most doctors are unskilled to properly manage your hormones are they are also afraid of prescribing TRT do to the stigmata surround it.
If you ever do manage to find a doctor that agrees you need TRT make she he/she understands you will require injections at least EOD or every day since low SHBG guys tend to excrete most of their T into your urine which is why you require more shots. Most docs don’t know this and have these cookie cutter protocols designed for everyone, for TRT to work it needs to be tailored to your pre-TRT labs otherwise you will feel worse than before you started. You’ll likely go through many doctors before you find one that will help you.
Also a poorly functioning thyroid will have some of the same symptoms as low T and will also lower your SHBG. If you wish to have kids HCG might be necessary as will an AI.