Small steps, think about finding a happy medium between the two. I've been at both ends, and have now found a place in the middle.
I have a close group of friends and i tend not to go out without at least one of them, otherwise i feel very anxious.
I had to take it in small steps though.
for instance starting with cinema, small pubs, meals, quick things, then building it up.

October 2009 i went into the worse depression ever, was even hospitalized, then it was getting close to New years eve and i knew how heartbreaking it would be for if i was at home on my own on New years, so i forced myself to go out, and i did enjoy myself, even thought i spent the whole day worrying and feeling horrible, and i had to make sure i would have my friends with me for a least three days with me so i didnt feel an awful anti-climax, but after that i thought i was cured and tried going out all the time, at the end of every night, i'd find myself suicidal and crazy and spend the next week in my house, feeling awful. So it wasnt worth it in the end.
Its taken me about a year to get to the point where i can go to someones house with one of my friends and not know anyone else, and i still dont enjoy myself as much as i once would have.

There's no reason why you cant enjoy a healthy social life, but it takes, time, effort and you have to be really careful you're not doing too much. Dont let bipolar beat you, but also, dont try and beat bipolar, just adjust your life to cope with it.

I hope this helps.