Yes you need to work on getting your feeling across. If you honestly feel you're not getting what's rightfully expected in a relationship then you need to communicate that...thoughtfully, and non-accusatory, of course.
Just because his girlfriend doesn't have a job doesn't mean she can't go out and get a hobby to do on the one day a week you and your bf both have off. Ask her to go to the library or movie theatre or something. (If you think she's freeloading off y'all maybe she could use that day to make it up to you by running errands.)
Secondly...what's good for the goose is good for the gander. If he gets to be poly and have a second partner, there's no reason you can't have one too. In fact, it's extremely unfair and hypocritical that you couldn't. (Unless you just don't want one---but it should be YOUR choice.) And for that matter, she should get one too. (That would certainly get her out of the house more.) Just because your bf is bi doesn't make him the only one capable of having two partners! As a gay poly, trust me on that one.
Thirdly...more communication. Anytime you have three or more partners under a roof you need to make a mandatory roundtable once a week where everyone meets regularly (say, Tuesday night dinner or whatever) every week and thoughtfully, honestly, communicates openly their honest thoughts about how the situation is going. Emphasize the good as much as you do the bad. But whatever you do, make sure everyone gets equal time to discuss how they thing the arrangement is working. How can your bf do a better job making you happy if he doesn't know what you want or need? How can she know what she's doing right or wrong if you don't honestly open up about things? It's a crucial thing. If they are mature, they'll use this as something construction. And if anyone takes something personally as an attack, then they're probably not mature enough to handle this type of relationship. Polyamory is NOT for immature people---everyone has to be adults! Gay, straight or bi...male or female....if you sit down and honestly discuss your feelings, and if everyone really does love each other, then things should go better.
However...the flirting, and displays of affection between other partners is just something you get used to in a poly situation. You'll have to adjust to that one. But again...you should be getting your piece of the action too. She'll have no right to complain if you're making out with him in her presence, either.