How to know if my cat needs a friend?

I just started working a new job and im not home during the day very often. My cat has been keeping my up all night. She never really used to do this. Constantly jumping around everywhere. Biting my feet, chewing my chargers, knocking things down. And even when im home just constantly jumping and attacking me and it’s getting really bad. The only change is that im gone more often. I try to play with her when i get home. But I don’t think it’s enough. My cat though is very anti social. I think she may have anxiety. When people come over she sits near us but if anyone tries to touch her or play with her (even me) she hisses and runs off. She doesn’t attack though. I took her over to my sisters house (my sister has my cats sister from her litter) and she hid the whole time and hissed at my sisters cat (never hit though) im wondering if it’s a good idea to get another cat? My cat has a lot of energy and is very playful but also doesn’t like other cats and people (unless she’s seen the people very often she’ll give in) is it a long process or is it a bad idea?