Following up a bit more on the good info the previous poster provided...
While with Testosterone you can just say Testosterone and be pretty clear you mean Testosterone.
Testosterone and Estrogen are somewhat misleading to compare.
Testosterone as you probably know is an Androgen, Androgens and Estrogens being the class of chemical compounds that induce development of male or female characteristics respectively.
Males have a relatively simple endocrinological (sp?) system compared to women. Testosterone being the primary sex steroid.
Women on the other hand have 3, of which Estradiol is the most analogous to Testosterone. So it's the one you want to be looking at.
From memory, I would probably want Estradiol to be a little higher than that, but this depends on if I'm thinking of the same units of volume, so you may want to look it up yourself on the blood references available on the internet.
For interests sake, Estrone is the estrogen most commonly associated for menopausal years. As far as I know the only common HRT supplement that works using Estrone (and various other non-human estrogens) is Premarin.
Estriol is the Pregnancy hormone, I'm not aware of anyone taking it for TS HRT reasons.
Sometime you may want to do if you can is ensure that when the doctor makes up the pathology request, or equivalent in your country, that they mark you as female for the labs.
With most health care systems they don't care about the different sex selection in terms of billing, but it will mean the pathology labs working up your info will use the female reference ranges on the report instead of male. Makes for a simpler read.
Hope some of that helps!