I don't think an expensive fitting session is necessary although I bet it'd work. A lot of people get fit dialed in pretty well by trial and error.

Your fit on this bike does look uncomfortable! See how your arms are stretched out straight? That indicates right away that you might benefit from a shorter or higher reach to the bars. **** man, there's like a foot of drop between the seat and bars---no wonder youre hurting. As well it looks to me like you might benefit from lowering your saddle an inch or three. Maybe you should get a normal frame for long rides and keep the ridonkulous foldie for shorter city rides.