I'm a low SHBG guy as well, and my hormones are all over the place. My old regimen was a shot of 50 mg twice weekly and 250 iu hcg EOD. My levels were as follows:
TT = 582 ng/dL (240-950)
Calculated FT = 313 pg/mL (90-300) --- HIGH
SHBG = 8 nmol/L (10-80) --- LOW
E2 = 13 pg/mL (27-54)
Fasting Glucose = 87 mg/dL (60-109)
A1c = 4.9% (3.9-6.1)
I, like you, have yet to feel any noticeable effects from the testosterone. I've switched my dosing to daily subq and my doctor has lowered the dose to 12 mg/day (84 mg/wk).
I'd say the best course of action for you would be to get A1c and fasting glucose checked, as metabolic syndrome is a common cause of low SHBG. As for me, I believe the cause to be genetic or something equally shitty, seeing as my labs look ok.
All this being said, you've only been on treatment for 2.5 weeks and it can take up to 6 weeks for levels to build and stabilize. It might be best to wait it out and see what happens. For me, I've read that some have had success with test propionate, and I may look to that avenue, and if you continue to feel poorly, it might be worth looking into for you as well. Best of luck! This is a tricky and often overlooked problem.