Relatively low E levels but adequately suppressed T during monotherapy?

I've been on HRT taking 5mg of EEn every 7 days since July of last year, and I've just received the results of my second blood test.

After I took my first test, I was shown that my T levels sat comfortably at 1.2nmol/L while my E levels were at 491pmol/L, which according to all the literature I've observed is lower than it should be for someone doing monotherapy. Ideally it should rest at around 750 to 1100pmol/L, apparently. However, I decided to wait, assuming my strange levels were just due to me starting recently.

I've now received the results of my second test and my levels have both dropped to 1.0nmol/L and 462pmol/L, respectively. This is despite me increasing my dose by 1mg, just because it made me feel clearer.

Is this something I need to follow up on? To save on costs I only test T and E, but is there anything else I should test? I'm aware the only factor for feminisation is low T and a decent amount of E, but this still seems a little low for me?

I feel fine, personally. The only noticeable effect I've noticed is a slight softening of the skin, though - not too much in the way of emotional changes or breast growth, although still some.

TL;DR: 5mg then 6mg of EEn since July 2024, E levels are lower than the reported target despite the fairly high dosage, but T is still suppressed.