How to be more sociable?

So...my dad just passed away, right? And at the funeral I talked to all my relatives like I never did before. And I am not a talkative person. I already played all my cards and exhausted all my dialogue options. And they all expressed their wish to keep in touch, but I just can't...????? What do I do??? I know this is what normal people do and this is what a family should be like, but I, my sister, mom and dad were never really sociable to begin with and after I and my sister grew up we also kinda stopped going to family functions. And idk... it's just weird. I have nothing to brag about or anything to tell others. I also don't care much about their lives either. And idk...they kinda make me feel guilty or like I owe them something, dunno. Guess I give off friendly energy when I try my hardest to be social, but it's very exhausting for me and it's even harder when I have to deal with relatives. So wtf am I supposed to talk with them? I'm ok if they take the lead and talk mostly about themselves, buy as soon as I'm supposed make a more considerable contribution to the convo besides nods, animated facial expressions and noises, my brain draws a blank. It's not like I can open up and be honest about things regarding myself. I also have no perspectives regarding my future and I am not proud about what I've done so far either...so I'd just rather not talk about my life. With the older folks it's better, because they mostly wanna yap, but the younger ones are interested to hear what I have to say and tbh I feel like they're judgy too.
Wtf do I talk to my relatives about when I don't feel like talking??