Of course it is the finasteride - anyone who tells you different is full of sh*t. You messed around with your hormones and you've paid the price for that. Simple. It really is such a sad state of affairs when people prioritise vanity over their health - and messing with your hormones can have serious long term effects.
Hormonal issues would have lead to a lack of morning erections. That said, TS should still check them out