Thanks for the responses. Let's get into some help for you. =)
BA's and UX designers have a lot of overlap, and in this case it looks like the BAs are doing some of your work for you and not leaving you much room to make your own decisions. But it's good to hear you're working with the developers and they're giving you helpful feedback on whether things are feasible. That's good.
A big part of doing UX is having the guts to argue the case against any approaches you don't agree with, and then working collaboratively towards a better solution. To do this takes patience, courage, time to do your own research, a lot of homework and fact checking, and practice in forming a solid argument and being able to deliver it. A UX role needs to help find the sweet spot between the business requirements and the needs of the users/customers. You're the customer's own advocate working within the design team. But you can only be their advocate if you know what they're thinking and feeling via research, testing and talking with them directly.
A big problem for you is that you'll find it difficult to counter a BA's or developers or manager's suggestions/requirements—you're not getting any time to do your own research and thus not getting time to generate your own opinions. Two critical elements that define a UX designer are research and iterative testing. If you're not doing either of these, it's difficult to say you're doing UX work. Hence I empathise with the corner you're stuck in! You're right—you're hungry for a more 'pure' UX approach.
Are you able to work more collaboratively with the BA's, to bring the customer voice to their work? If that really can't work, and you don't have time to do your own research/testing tasks, then it's really difficult and you may need to consider working elsewhere if you want a more 'pure UX' approach.
But let's not give up on your workplace just yet. If you play the long game you might be able to help show your manager and teammates the benefits of a user-centred design approach. There are some solid arguments for it. You can forward them online articles, and gently encourage them towards considering it. However, it doesn't work if you hammer them with reasons why they should change. Instead, you should try to show them and prove it.
I know exactly how hard it can be as I've worked in some similar places myself.
Here's one article I wrote that has a few principles you might like to get working on: How To Apply UX In An Organisation New To User-centred Design
Let me know your thoughts, and keep the questions coming.