Ahh Succession Laws
They take a bit to understand indeed, and sometimes I still get surprised by them, but they can be very powerful if you use them right. For your daughter, assuming your Laws were Agnatic-Cognatic, your daughter should only have inherited when there were no more eligible males as Sons/Grandsons (Note that being a Bishop makes them ineligible), but I can't tell without the full picture.
While such a situation is very dangerous indeed, there are few things you can try to save your Dynasty line when you end up like that:
-Divorce, remarry properly and get kids (preferably a son). Then any sons you had with the previous husband (+daughters if you only have a daughter) need to be either excluded from the succession (If you're Catholic, you can do this by giving them a Church Holding or appointing them as a heir to one if you have Free Investiture) or simply killed off.
-Try to switch Succession Laws to Elective (Very powerful and stable, but can go wrong very quickly if not properly managed) so you can choose a Heir from your Dynasty or Seniority (Can be very powerful but also very brittle) so the oldest member of your Dynasty inherits instead of your kids.
Of course, this won't go without some resistance or problems, but at least it'll save your Dynasty!
Starting out as an Emperor or a very strong King can be very boring in my opinion unless you have some plan to give yourself a challenge (Become a Heretic for example). The journey towards becoming that King or Emperor and all the setbacks in between is the fun part. I think that's where CK2 also succeeds very well: It's not about winning, it's all about the journey (Which is why CK2 and BM are so damn addicting and fun). Having no setbacks makes the game boring! I generally quit games before the end if I've become that big and powerful as I've already completed any self-set objectives. Playing a Count or Duke under a King is much more fun as you try and manipulate your way up to the top.
Starting out in the Iberian Peninsula as a Catholic is one of the more difficult spots you can start at, as the Sunnis will quickly join forces against you while you have two brothers eyeing each other's thrones instead of joining forces together, but can also be very fun. One of the recent patches gave the Catholics there a bit of a buff so they at least have a chance at surviving. A good bet there would be to try and ally with France and pray France stays stable enough to be able to help you. Basically, it's all about surviving until the first Holy Order appears, after which you can can actually start fighting back a bit.
My last game was actually as Galicia, and I got very lucky by the Sunnis fighting each other (You can try assassinating strong Sunni Rulers and hope for a succession crisis as well) while my two brothers beat each other up, allowing me to conquer Leon very quickly without too many casualties. Never really managed to ally with France without them in a Civil War or replacing Kings. I then had two Jihads called against me for Galicia, lost that Kingdom and started to lose regions in Leon. I was in the middle defending in a war with my last Duchy at stake when the first Holy Order appeared. That's when things turned around. Most fun I ever had. Rest of the game I spend keeping Galicia for myself, while, instead of expanding, trying to install various Dynasty Members into the independent Kingdoms around me (That wasn't that great of a success though, as the inheritances just make a whole mess of that if you aren't careful).
Another very difficult, if not the most difficult, start is Abyssinia. They do not have access to any Mercenaries or Holy Orders, their lands and tech are terrible, are Orthodox Heretics with thus no Allies, and are surrounded by Muslims for whom they are just easy pickings. This guy here is doing a playthrough as Abyssinia (Starting out several patches and changes ago), having the worst kind of luck yet holding on and it's absolutely hilarious and fun to read:
http://forum.paradoxplaza.com/forum/showthread.php?601251-In-the-Shadow-of-Certain-Painful-Doom-AbyssiniaI don't want to spoil anything, but I really recommend reading it if you have the time.
