You will be fine:
In a situation like this, the Na+ ion concentration is the primary concern, rather than the bicarb (HCO3-). While it may place some undue strain on your renal system, acute hypernatremia (too much sodium) is of little concern as long as you don't have some form of renal insufficiency--the kidneys are quite efficient at normalizing plasma tonicity.
In the future, I would say take much less than 4g of NaHCO3 to increase absorption/decrease excretion of PO amphetamines....also, chasing a large dose of bicarb with CaCO3 (Tums) is not ideal, as it COULD theoretically contribute to a hypercalcemic/alkalotic state (too much calcium and increase of blood pH)--which at this range is again very very very unlikely.
In short, you will be FINE. But next time don't ingest that much bicarb regularly esp when combined with an alkalizing calcium supplement such as Tums. In extreme cases this can result in something termed "milk-alkali syndrome," which is clinically characterized by hypercalcemia....no beuno.
Just drink lots of water--that should aid in the normalization of plasma tonicity etc...
On an side note, I have found that Alka-seltzer gold (effectively Na/K citrate) achieves urinary/enteric alkalinization without a heavy sodium burden and can increase amphetamine absorption and decrease renal excretion.