She's a sponsor for a TS group? This blows her objectivity. And she came up with this diagnosis during the first session?
Gender therapists aren't supposed to diagnose you as a TS or not, they're supposed to follow your lead. It's not as if there is a blood test for this. When they have clients who feel they are TS, gender therapists should make sure there are no comorbidity issues and also address any mental conditions that may confuse the issue. Two such examples are depression or addictions.
In the past few months your threads have indicated that you've been in a rather thick Pink Fog. This is common after CDers come out to their wives. But, be sure to not mistake the euphoric feelings you may be feeling for a conviction that this is what it feels like to be a woman.
You may well be TS, no one in this forum can make any judgements. But you need to know that the percentage of transsexuals among the community as a whole is very small. Despite this, I think it's safe to say that just about everyone gets these strong feelings at one time or another. I would give it several years of exploring the cross-gender expression to the point when it is no longer a new, exciting thing, before making a final determination that you are TS. If you do decide that you are, then please do seek a gender therapist who will test for the conditions stated above before writing a letter for the endocrinologist.