You should be able to see the tibial spurs on a Grammostola. Sometimes they are difficult to see on arboreals because they are smaller and have longer hairs. Certain species, such as T. blondi, mature without any tibial spurs at all. Regardless, all mature males have palpal bulbs on the end of their pedipalps. They are bulbus, dark colored, and usually shiney ends to the pedipalps of a mature male. They look like hooks that are folded underneath, which does look like a pair of boxer gloves. 5 months without a molt really isn't a very long time for a Grammostola. They are very slow growers and go for long periods with out eating or molting. You should be able to do an internet search for photos of palpal bulbs and tibial spurs. You might even find some photos of your spiders species. Good luck!!