We had ours pumped in January one year without any freezing problems – I was too busy fishing in fall to have it done earlier… I suppose it depends on the system, but you may want a second opinion and could maybe have a partial pumping if needed???
If it was / is a clog, be careful what you put through it for a while – nothing extra for paper, feminine hygene items, or garbage disposal use. All of which is good advice for every day use with a septic system, even if you aren’t having a problem.
And yes, you should be able to see the water run into the system. While you’re looking, I’d suggest again using a hook to remove any paper build up where the waste line empties into the tank to clear that area.
If you have “dry wells” you could also take a long piece of pcv, etc. and probe the vent stack to see if they seem full.
Good luck.
Dan
P.S. Another thing that could point to a full tank is if the system got a lot of use earlier today or yesterday – multiple loads of laundry, etc. and that the system got overwhelmed with waste water.