Ok, I think I know why. You were probably on pills back in Nov and then switched to injections, right? Estradiol, when taken orally, STRONGLY stimulates the production of SHBG which strongly binds T and decreases significantly free T. Whereas, when taken non-orally (injections), SHBG is MUCH less stimulated, therefore the increase in free T.
The reason why oral estradiol increases SHBG to a far greater extent is because, taken this way, much more of it circulates it through the portal vein on its way to the liver, where SHBG production is triggered by estradiol. Taken parenterally (injections), a far lesser amount goes to the liver so SHBG production is weakly affected.
In the end, I think what matters most is how you feel and physical results. If those are good, then you needn't worry.
I've had my levels tested on injectables where up to 3,800-3,900 pg/ml was shown. I've been on the same dose for 1 yr + and I feel good and all other health parameters are fine. Do realize that pregnant women have levels ranging from a little less than 1,000 pg/ml to up to 75,000 pg/ml. You're in the VERY low range of that.
The doctor should decide whether these levels are appropriate for you or not. I'm just throwing ideas at ya. 😉