Hi...new here and looking for some feedback.
A 14 year old who pays her own cell phone bill every month is a lot more responsible than the majority of her peers. It sounds as if she has earned a little more privacy for herself. I'd let her have a FB account, and just lay down some ground rules. You reserve the right to her passwords, but won't use them to check up on her unless you suspect there's trouble. And even then, you'll tell her that you're checking her posts.
IME, all teens, unless they're on drugs or have serious mental health issues, respond very positively to openness and trust from their parents. And the more responsible and trustworthy a kid is, the more freedom she needs to grow.
I think Music is right--your #1 problem is that you and your husband do not agree on basic parenting rules, and that he does not tell you when he overrides you.
My DD got a FB page at about 14, maybe 15, and it made it a whole lot easier to keep track of what was happening with her when I insisted that she friend me.
It appears that you & your DH don't agree on whether your DD should have a FB page, which is one problem.
The rule in our house is that I have her codes until she graduates highschool (which will be 17 for her.) If we suspect a problem, if she's breaking rules or we are concerned that she's hiding something important we have the right to go through her stuff. Plus, DD has had issues with a cyber stalker (a nasty girl who hunts her down online to leave nasty grams even though they haven't seen eachother in years and don't even live in the same county.) There was a period between 13.5 and 14.5 when she got very secretive, emotional and we were worried. I didn't read her texts but since she was on my account, I could look up when she was texting (after bedtime which was against the rules) and to what numbers. I did look up a couple numbers on her contacts lists because they were texting her at like 1 or 2 in the morning. I looked at her friends lists on FB ever so often as she was ammassing tons of "friends." I didn't read her personal messages but I'd check her page for appropriate content. During the "dark days" she was connected to personalities that weren't good for her.... they weren't dangerous, just self-absorbed users. DD figured it out, cut ties on her own and is much healthier now.
I am in the same boat as you. My 14 year-old daughter joined Facebook without our knowledge and consent! the only way I found out was that my sister-in-law was asked to be a friend and wanted to know what was up. She knew that I did not want
I have a 13 yo SD, but the expectation with both her phone and facebook/email is that dad always has her password, and will monitor from time to time.
I would not be checking texts unless I had a very specific reason & thought there was a big problem.