Roughly a bit over USD 11 Billion, that's how much the PML(N) Government left in the coffers. Please also remember that PML genuinely believed that they would come into power again, they almost did, which is indicative of their comfort with the budget and the reserves.
As for the real demand for USD, yes that too is a factor but only for interbank transactions as all international (legal channel) payments are made through SWIFT.
Sadly, you have not considered the fact that we are importing things which we either don't or can't produce/manufacture. Our top 10 imports are:
01. Oil Products: 28.4%
02. Machinery (including Computers): 10.4%
03. Electrical Equipment: 7.2%
04. Iron/Steel (including Scrap from Ships etc.): 6.1%
05. Chemicals: 4.6%
06. Vehicles (including items assembled in Pakistan): 4.3%
07. Plastic/Items: 4.1%
08. Animal/Vegetable Fats, Oils etc.: 3.5%
09. Oil Sees: 2.4%
10. Cotton: 2.1%
Of the above, we CANNOT produce/manufacture items 1, 2, 3, 5, 6 and 9 which sums up to 57.3% of our total import. Out of import items at number 4, 7, 8 and 10 (15.8%), a good 8-10% are things which we cannot produce/manufacture and will need to import. These are things for which we simply have no local alternative.
Not just that, things which are being produced locally are sub par, of low quality and more expensive than the imports. This could also be because of higher cost of production (electricity and imported machinery, raw material etc.), monopoly and greed.
Coming to your example of chocolates, imported and local; imported chocolate will become more expensive with the rise in USD but so will the local chocolate as we import raw material (cocoa etc.) and machinery (including consumable/running/spare parts). Also, with the PKR losing its value, the local chocolate will further suffer because it's value will decrease with the same price and hence will have to increase. Worst of all, you can rest assured that the imported chocolate is of higher quality (ingredients, quality control, packaging, machinery etc.). Consider the 1.1 million (USD 8,570) Alto and compare it to its Japanese counterpart (USD 5,200) and you would be amazed at the difference in quality, comfort and safety of the cheaper Japanese version versus the more costly Pakistani version. With the difference in currency and other import strangulation policies, you are essentially forcing the common man to 'compromise' on his family's safety and luxury for a much more expensive but inferior vehicle/product/quality of life.
Not to mention the excise duty Government gets from imports. Contracting imports lead to contracting duty and hence impact on deficit gets subdued.