Yes, Estradiol is the test that should be ordered if you're taking testosterone.
Ultimately - there are no conclusive studies saying that testosterone is harmful to female reproductive health. It is a myth that has been out there for a while that transmen need to have a total hysterectomy within 5 years of being on T as a cancer preventative. Yet there are no studies that come to that conclusion.
So I would say, if this dose you're currently on is getting you into a range you're happy with in terms of both E and T, then I wouldn't change anything. Everybody naturally produces at least some testosterone and estrogen. If the levels you're at are working for you, don't reinvent the wheel. There's no harm in keeping it the same.
Re: blockers, I don't know that you'd be any worse off health-wise generally, BUT I'm not sure if there have been any studies on them regarding long term use. The better long term option, I think, is to find a dose of T that works enough for you. It sounds like the one you're on or lower would be good, provided everything else is in good shape.