I feel fine about referring to myself as "an EA" in contexts where this is convenient and doesn't imply major "identity" or "ideological" commitments. And indeed I sometimes do so.
In many ways the label does seem quite descriptive of my views and career goals.
I don't feel like I identify as an EA in any strong sense, or like I would want to describe myself as such no matter the context. For me, this partly has to do how I think about EA relative to other life goals. The way I roughly see it now, maximizing impartial goodness is one of the most important goals I'm pursuing; but there are also other, more personal goals. I feel like tying my identity to just one of them would "privilege" that one goal at the expense of others, in a way that messes with my way of internally resolving conflict between them (and of course such conflicts sometimes to come up). This feels true to me even if it turned out that in some sense, maximizing impartial goodness was my most important goal, or the one I cared most about, or similar.
For a couple of months during the first year after I had encountered EA I was more in a mindset of "EA is the most important/only goal, and I can pursue other goals only insofar as they're instrumentally useful or it would be psychologically impossible for me to not pursue them". Partly this was due to bad social influences. This isn't exactly the same as "identifying as an EA", but I now think my mindset at the time was both unhealthy and instrumentally harmful for my long-term ability to do good, and so it's one key reason for why I'm skeptical about, in some sense, "emphasizing EA too much".
[I wasn't at the Leaders Forum 2019.]
You've drawn a good distinction here, and I should revise what I said before.
In my previous comment, I lazily copied the explanation I use to tell people they shouldn't capitalize "effective altruism" ("it's not a religion"). As you say, it doesn't fit here.
The thing I don't like about applying "-ist" labeling to EA is the addition of "effective", which (as many others have said) seems to presume impact in a way that seems a bit arrogant and, more importantly, is really hard to prove.
Are you a pianist? Yes, you play the piano.
Are you a virtue ethicist? Yes, you believe that virtue ethics are correct (or whatever).
Are you an altruist? Yes, you give some of your resources to other people for reasons outside of law, contracts, etc.
Are you a great pianist? ...maybe? What defines "great"?
Are you an effective altruist? ...maybe? What defines "effective"? You might hold a bunch of ethical beliefs that lots of other people who use that label also hold, but it seems unclear exactly which set of beliefs is sufficient for the label to fit. (And even if we could settle on some canonical set, the word "effective" still seems presumptive in a way I don't want to apply to individual people.)