I think you may feel better tonight even though you took a smaller dose because tramadol is metabolized more efficiently when tramadol is already in your system. Since the metabolites are way stronger than tramadol itself. The metabolites also have a longer half life, I think around 9 hours, so yesterdays dose was still active in your system when you took today"s dose. That's why I like to stagger my dose. I will take 50-100mg initially then 45 minutes to an hour take the rest of the dose.
I'm a little more opiate tolerant than you 50-60mg oxycodone. I'm no doctor and this is just my opinion, but I feel like the SNRI effects are more prevalent in the first hour or two. This is usually when I get an energy boost, a couple mild short rushes of euphoria and am in a sustained elevated mood. As two hours pass I feel the opiate buzz taking hold, although significantly more mild and somewhat different from an oxycodone buzz, I still get an opiate itch. I've never came close to nodding on tram, but once I do go to bed I can sleep for 13 to 14+ hours easy and wake up feeling great.
I highly recommend smoking some weed a few times in the first few hours after dosing with tramadol. Tram definitely potentiates marijuana for me to a great extent.
Just keep in mind that tram stays in your system for much longer than most opiates. So don't go taking 400mg as an after dinner dose then decide to dose at brunch the next day. Repeated high dosing on consecutive days greatly increases your risk of seizure.