If you want you can now take a break and build up your cities, for a couple of years. Never, EVER trust the seleucids they are treacherous bastards and their word means nothing!!
Do this with the numidians in lybia with the diplomat that is provided for you. Don't worry because they are all rebel towns Also build a diplomat in jerusalem and send it to dumatha(long way) to obtain trade rights and alliance from parthia. Once you take one over, enslave them and build 1-2 peasant units, then keep going. The numidians are very passive they will never betray u.
The first thing you want to do is take all your good troops in alexandria, memphis and thebes and build and army to take petra, bostra, and palmyra in quick succession.