An observation about your current operations.
You're operating in a very unefficient way in terms of scheduling. You have the following services:
HAM 4/weekly (demand could support 2/daily with the E170)
MUC 3/weekly (demand for 1/daily with your A319)
BCN 4/weekly (demand for 2/daily with E170, but the 1900+NM distance makes the Embraer very, very inefficient, so a 1/daily A319 service would be better)
DXB 3/weekly (demand for 2/daily with E170)
For every route you have, regardless of how many times per day/week you fly there, adds to your overhead costs. Therefore, it is more efficient to have as few routes as possible and to take the maximum out of those. A better plan for now would be for example to axe MUC, BCN, DXB and focus your E170 on the HAM route (+ if it fits the schedule, a 3rd flight to somewhere closer by, TBS-KBP seems to be free of competition), while keeping your A319 on MAD and FCO routes.
And yes, as Alexgv1 said, fit more seats into the Embraer. 76 is a good figure, keeps the comfort level at "fair" and gives you room for another 9 paying customers.
Good luck, cheers.