Baby take feed only after making him diz

Hello, My son is 3.5month old and he is on breastfeeding only. Everyone says that at this age we should feed babies on demand and not every hour or 2 hours. My son won't ask for feed for hours and he plays for hours without feed. We have to feed him at some interval and that time also he won't take feed in awake condition. For feeding him, we first need to make him dizzy little bit and then only he takes feed. So is it okay we are doing this?? Because if we wait for him to ask for feed then he won't get enough feed by himself and there would be an issue with with gain as well. With all this efforts he is now 6.1kg. pls suggest something to us how we should proceed so that he can take feed in awake condition as well or as for feed by himself???