TL;DR -- It is good to push your boundaries, just a little
I'm going to suggest that you examine your motivations.
Are you worried about general mental health effects of isolation? That's the sense I get from your question. Not an expert, but I will suggest that contact with others does help to "pull us back" toward the mainstream so that we don't get too eccentric. The deal with that though, is that you don't really need huge amounts of associates or parties to get that level of interaction. As you already have your group of "known people", you likely have enough in terms of not being the weird recluse.
Are you worried about being lonely? Only you can answer this, because you are the one who knows. If you feel like you don't have enough social contact, that's your answer right there.
Are you worried about impact on your professional life? Like it or not, bonhomie and general chitchat ability do have an impact on business success. If you're personable and likeable, people will like you more, and this can be the feather that tips the scales when favors, promotions, and so on are in the balance.
Do you just feel that you should get out more? You're probably right. I'll ask you this, though ... does it have to be these 'large parties' you're talking about? That is, there are huge amounts of places and situations you could pick for your socializing, many of them quieter and lower-stress than these parties you speak of. Here are some thoughts...
You could volunteer for Second Harvest or the like. You will meet people, but fewer at a time, and there is a built-in "something to do" so there's not so much just awkward standing around
You could check out ToastMasters club. It's a fun activity, and they are pros at handling people who are a little socially insecure.
Whatever your hobby is, there's a club for it. You could check out their meetings, again have a built-in something in common, and probably have a pretty good time.
Heck, you might just call up your regular "known people" a little more often and invite them out to dinner.
Point is ... it doesn't hurt you, and probably helps you, to nudge yourself into a little more social activity. The key is to pick something you actually like doing, and don't stress yourself out over numbers or frequency.