I suspect no one wants to get involved because, unfortunately, the answer has to be - depends on the beams, depends on the weight.
If there are similar houses around you could ask if anyone else has done the same job. Old building is not necessarily about to fall down and old builders tended to use big beams - they couldn't calculate what they could get away with.
Any chance of finding a friednly surveyor, builder, architect? You could trying to get someone professional in for a specific purpose for a fixed fee. They will probably charge less if you don't want a written report.
As long as you don't do anything really daft on the weight front (e.g. filling the loft with books or tanks of water) you will probably be OK.
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