Dear Neha,
To add to Harish's views:
From the sounds of it, you've been asked to be the conduit and central hub for information flow among various departments as well as from those departments to the director.
There can be a number of operational, structural, and efficiency reasons for this to have happened.
But, what you don't have is any specifically mandated authority in any of those departments. Essentially, as an EA to the Director, your primary role still remains as a 'gatekeeper to the boss'. And, it is not uncommon for such 'gatekeepers' to be allocated additional responsibility in relation to collecting departmental reports, departmental memos, and other similar documents/MIS, etc., for forwarding to the Director.
If seen in this vein, your role hasn't changed. What has expanded though is the scope of your role which now encompasses numerous other departments. Maybe your boss realizes that it's more efficient for him to have a central figure from 'head office'—to give an analogy—responsible for providing timely information at the established frequency.
Don't forget that conventionally, an EA's role is one of far greater responsibility and value-add than a PA. I won't be surprised if one day your boss requests you to collate all departmental reports and then create one overarching or master report from that data and present him with that master report only. While that shouldn't be surprising for an EA to do, it definitely is not something that can be traditionally expected of a PA.
But, when you say that you also 'meet with clients'—that definitely doesn't fit the curve of an EA with additional responsibility. Probably this is because you are a good communicator with a command over the language that exceeds other people in your office. If that is the case, it makes total sense for your boss to request you to assist in client interaction as well. The question though is whether you are in the room with clients with your boss as well, or you have independent meetings with clients.
If it is the latter, then you should celebrate. Because your boss has identified skills in excess of what he hired you for. In this context, my suggestion is to enjoy this recognition of your skills, learn the ropes (in your case you have the added benefit of an open door to the boss. So, he himself may be your teacher/trainer/mentor—which is a rarity for most staff in the majority of organizations), make your mark and then, and only then, have a conversation with your boss for reviewing your role, your responsibilities, your KPIs, and of course—your remuneration.
Personally, I totally agree with Harish that you are on a golden wicket to learn cross-functional skills. And, working in an SME with 150 employees (which isn't a small SME by the way) is a fantastic opportunity to learn, make mistakes, do better, and eventually hone multiple skills which would be very difficult if not nigh impossible in a large organization with a not-so-flexible structure.
Make sure you keep a record of all key events/tasks/responsibilities you perform as you go along. You'll be amazed at how much you'll accumulate in 6–9 months which I am sure will turn your current CV on its head and make you a really appealing candidate for other employers.
I wish you all the very best and have fun!
Regards