You're not doing anything stupid. This is the single most common editing problem there is, and the darker months make it worse.
Two things are going on. First, your screen is far too bright for the room. In a dark room with the backlight cranked, everything looks luminous, so you pull exposure down to compensate and end up with files that are a stop darker than they should be. Second, a budget laptop panel is probably nowhere near sRGB and nobody has ever measured it, so its idea of middle grey is a guess.
Fix the first one for free tonight. Turn the screen brightness down to somewhere between a third and a half, and put a lamp on behind or beside you. Edit there and see if the problem mostly goes away. It usually does.
A calibrator (around £150 for a basic one) fixes the second, and imo it's a better buy than your next lens. Target about 100-120 cd/m² and D65. On a cheap laptop panel it can only do so much though, the panel is the panel.
And check the histogram, not your eyes. If the woodland shots are all piled up on the left with nothing past the middle, they're dark no matter what the screen tells you.