Bathroom Plumbing Problem, Why wont the sink/tub/toilet drain properly?

Septic tank has been recently pumped

I assume the problem is recent and by properly you mean - slowly. Check to ensure the drain lines do not have some sort of blockage, either from natural build-up or a foreign object accidentally getting flushed into the line. Another possibility is that your drain line may have a clog in the vent stack. When you look at your roof you may see several pipes coming through. These are your plumbing vents and allow air to escape the lines so water may flow down. I have seen times where birds (or other flying animals) have built nests or been stuck in these. Could be as simple as tree leaves/seeds built up as well, assuming you live in a wooded area. (All the above has happened to me) Unplug the drain and/or vent and this may take care of your issue. If not, rent or call someone who has a camera and follow the drain line to see what the obstruction is.