i think your dosage of T is too high and that's why your body wants to convert so much of it to estrogen. you probably shouldnt be 940 the day before a weekly injection, 940 would be very high for a 20 year old.
having said that, arimidex has done wonders for me in the 2 months i've been taking it, and my E2 was only 48 after a few months on hcg. the doc prescribed me 0.5mg ED, which is higher than what most people i read about on msg boards take. i tried that at first, felt nothing for about 10 days, then all of a sudden i started waking up with the biggest erections id experienced in many years. and libido came back and now i think about sex all the time. just the hcg alone wasnt doing it for me even though it did raise my T levels. i have now cut back to 0.5mg EOD, which is still higher than most people seem to take, but it seems to be working for me. i read a comment on another more steroid oriented forum where a guy was saying to calibrate the arimidex dosage based on morning wood, because if it gets too low you wont have it, but if it's just right it will be huge and powerful. i now have morning wood every time i wake up, whether middle of the night, morning, whatever, so i am going to assume i am getting it right, dont have bloodwork scheduled for 6 more weeks to know for sure. before starting hcg i was getting it once every 2 weeks or so, then improved to about every other day, now it's literally 100% of the time and so strong its almost painful if sleeping on my stomach.
additionally my lingering belly fat is finally starting to come off. i'm 6'3 and have weighed in the 205-208 range for years, even though i work out aggressively and am quite muscular. i had no fat anywhere by my gut, none whatsoever on arms or legs. finally the gut has started shrinking and i weighed in the other day at 199. i think 195-197 would be an ideal weight for me, so getting close.
anyway the doc never even tested the E2 the first few times i went in, so dont know if it was high or not to begin with, or if the hcg drove it high. the doc didnt want to give me the arimidex for it being just a little high, but i insisted on it and am so happy i did. all i can say is, based on my experience, be sure your doc is testing E2, and demand an estrogen blocker if it's high. everyone is different, and you can find plenty of comments on other boards how someone had a bad experience on arimidex, but for me it's been fantastic.