I'm not sure how thick "pretty thick" is. If your stool is unformed then consistency is probably fine (i.e. not the cause of the issue). I'm not sure about fiber at bedtime - it never occurred to me to try that. I use fiber to thicken up food residue, so I only take it with meals. Your overall fiber dose isn't extreme, but the best way to find out if there's a connection is to experiment. You could try going a day or two without fiber supplements and see what it's like for you. The best dose for you can only be determined by trial and error.
Seven weeks is still pretty early, so your body is still learning how to manage this. All kinds of ideas have been suggested here on the past - you could search for them. I'd suggest a search word like "emptying." For example, some folks benefit from a small stool underfoot while on the toilet. Good luck!