Want to get pregnant

I have been with my partner coming up 3 years. We have a 19month old son and I am really wanting to fall pregnant again. Someone once told me when you have that feeling in your heart, head and belly that you want a baby that that is the perfect time to try, I have a large family with lots of children around me and that's just my day to day life being round children Mammys and daddy's. 

This is were my problem comes in.. 

I've spoken to my partner about trying for another baby and he just seems to brush it off saying 'yeah ok' that's all he doesn't seem into the idea what so ever.. I just don't know what to think about it because I'm 100% ready to be trying .. I just don't want to put something on him that he may not be ready for but yet I so am .