Missskyler,
What are your Testosterone blood levels?
If you have a low Testosterone, it will be difficult to build muscle. Taking Estradiol is the wrong hormone to put on weight without overeating. If you have testes, Estradiol will suppress your natural Testosterone production.
Working out will tone your muscles and give you a lean physique, if you work all the muscle groups properly. A modest weight gain of 20 pounds may be possible, but it is much easier if your Testosterone is at least in the normal female range.