LLB and JD are two different courses. Like I said, a JD is generally a graduate programme. Thus, you need to have obtained your baccalaureus degree before going for a JD. A JD may enable you to use the title Dr. in certain jurisdictions. The requirements may differ from institution to institution and it is best that you personally contact your preferred institution.

You can enroll for a Diploma in Law programme with an SPM qualification. You may subsequently transfer your qualification to form part of your LLB upon completion. However, you may not be able to practise in Malaysia as your qualification will not enable you to sit for the CLP exam.

You may apply for your LLB using the mature student route but in order for your to qualify to sit for the CLP exam, you need at least 5 years of relevant and proven working experience. I highly doubt that you would like to enter using this route as you have just finished your SPM.

Therefore, it seems that the best option for you currently is to do a Pre-U, whether STPM, A-levels or Matriculation. 

It would have been easier if you answered my repeated question above regarding the jurisdiction in which you would like to practise.