Trip to sg and bintan

On 19th you will return to SG, but there after? Are you going to stay in SG or you have inbound flight to Jakarta on same day or day after?

If you want to stay in SG then you must have a reason for frequent visit as there is a possibility that immigration officer will ask the same. You may have to show accommodation details in SG and return ticket to Jakarta.

You may write to ICA for any clarification.

@surya2k  yes I will be going to stay there again for 3 more days. should I write the clarification in advance to ICA?

Whatever you have doubt you may clarify with ICA. As I have mentioned you should have inbound ticket to Jakarta, accommodation details in SG, sufficient cash for your stay, as immigration officer may ask these proofs and reason of your stay in SG.

Next time avoid coming so frequent as there is a possibility that you could be denied to enter. Good luck

If you already have a booked return flight, which is within the original one month of visa, then a short trip abroad should not be a problem - because it is obvious that you are not (ab-) using this as a way to extend your stay.
But of course they may ask for the reason for your frequent visits, so better prepare a good answer!