Sorry for the error above @Gibbon (I input 300 mg/week every 7 days instead of the 300 mg you were doing every 28 days approx.)
Very likely you were up close to 3000 ng/dl at peak and now the 755 ng/dl 10 days after injection makes sense.
Sorry for confusion previous graph caused.
Graph as made assumes HPTA shut down from beginning and your injection frequency was long enough where TT levels don’t build up over time from accumulation due to previous doses. Nevertheless, the graph above would be representative after a few months where you would have no endogenous T being produced.