Bookworm,
There are a few traps for young players when it comes to weight control .... may I offer just a few thoughts which might be pertinent to your situation ?
(a) there are many errors to be found in inappropriate use of scales. Indeed, one occasionally sees scales which are, themselves, quite inappropriate for the intended use. I recall a case, many years ago, where a rebuilt classic taildragger was weighed on quite inappropriate jackpad cells. To cut a long story short, the test flight just avoided disaster and when the machine was reweighed with appropriate platform scales, the empty cg jumped aft a great distance.
(b) likewise if the weigh is made with lots of fuel and uses inappropriate "standard" sg values to account for the fuel weight. Also, one ought to check that the tanks called up in the AFM or TCDS actually are in the example aircraft ... I have seen just this sort of mistake cause acute embarrassment.
(c) check that the loading system is both reasonably pertinent to the aircraft and that the entry data, if it is a trimsheet style of system, are appropriate to the system's design. It is generally common for the weight control chap (or chap-ess) to design such systems using a datum position which differs from that suggested in the manufacturer's data. While we try to make such systems difficult to misuse, sometimes it doesn't always work out as well as we might hope. I recall a case where an operator was using one of my trimsheets (with a typical non-standard datum) and one of that particular fleet was modded and reweighed. The weigher, not being quite up to speed on trimsheets, thought to do the right thing by rescheduling the entry data - but used the manufacturer's standard datum rather than the non-standard datum for which the trimsheet was designed. Fortunately, the chief pilot, who was a friend of mine, couldn't quite make his load fit the system and thought to give me a call to check. Quite sobering.
(d) have you made a research check through the aircraft's weight control history ? That often gives a good guide as to where the error(s) is(are) ?
(e) is the aircraft behaving strangely in flight at your calculated forward cg ? If so, how so ?
I would be interested in your observations. The story, as you have given it so far, is a little inconsistent with what I have seen over the years with lighties.