lack of sex drive only 21!!

So I'm 21 years old. Me and my boyfriend have been together for almost 3 years now. We have a beautiful one year old son and everything is going good for us now. Except I have no type of sex drive, and he's pretty much a sex addict! It's brought some tension into our relationship and he's usually very understanding and doesn't push it but lately he's been a little upset about it and I'm not sure what to do. I will tell myself over and over have sex just to make him happy but then when the time comes I just can't force myself to do it. Does anyone else have this problem?! I googled it and it says it could be because of multiple reasons one sticking out is stress which yes I'm always very stressed. Two years ago my brother was murdered on Easter Sunday and the year before that my dad passed on Easter Sunday so every day of my life since then has always been stressful. Any tips to spice things up or things that turn you on that I could try?! I need help! Part of the reason why I love my boyfriend and our relationship is because the sex is amazing and he's the best I've ever had so it's not that I want to go be with other men or am over him.. pleaseeeeee help a girl out, anything is worth trying!