Angelique,
My Endocrinologist would say that your levels are on the low side, but still acceptable. My levels are in the 500 to 600 range when my blood levels are drawn one or two hours after taking estradiol sublingual. I get my blood levels drawn twice a year.
Each blood draw will give you different estradiol levels depending on many factors, such as time interval between last dose and blood draw, any absorption differences, how much estradiol is actually in the last dose you took, and of course lab errors. A few points up or down is not very important.
Premenopausal just means that your levels are similar to many other women in that age group. The question many doctors have not considered is that transgender women may need a higher blood level to get results in a timely manner. My Endocrinologist has much experience with transgender patients and had no problem putting me on a high dose right away.