Friendship expectations

I used to have a rule. Every friend got one strike. One mistake, one failure, and I no longer used the title friend for that person.
I thought at that time that I wanted my number of friends to be very limited. This was before friend had been minimalized by social networking, and my definition was as tight as my rules. It was appropriate few could qualify.
But the one strike rule was one to which I couldn't live up. And in reality, keeping my definition and rules so strict was simply a self-fulfilling prophesy. I came into friendship expecting to be disappointed, to be left, and therefore I did every thing I could to make it more likely.
Today I'm more likely to use the word friend in description. But in my heart, I'm not much more lenient.
Superficially, I'm a very social animal. But the reality is there's always a guard up, I'm always sort of inside looking out, peering over the character that is conducting the socialization. I'm now aware I'm fortunate to have a wide cast of acquaintances. But whether I'd internally admit many - if any - of them to the list of friends is highly questionable.
One astute person I know describes my usual haunt, with a standing cast of characters, as "easy." She claims the reason I choose the spot is because the others in attendance don't challenge me. And that although I'll sometimes complain of boredom, the reality is I'm most comfortable with the assurance I can coast. No one in the equation asks much of the other.
I know a young lady who I've described as a friend. But she's wildly inconsistent, disappearing for extended periods of time and becoming completely uncommunicative. Since I can't count on her, in my heart I don't consider her a friend. Some of it I write off to youth, some to personal issues about which she's confided in me but with which I'm uncertain she has come to terms. But the lack of unaccountability leaves me reticent.
Recently, a third party questioned our relationship to her. Without hesitation, she stated that she believed I'd do anything for her, that she could completely count upon me and I was therefore her friend. She'd never said anything even similar to that to me. But the third party passed it on with some incredulation at her vehemence.
When I've been in crisis, I've gone old school Texan. I don't turn to others. I try to "man up." It really doesn't work. While I'm internalizing, the pain is an infection festering. It's been my karma to have people unknowingly step up and do little things that catch my attention, make me call myself lucky. But it's been just that, luck, that has kept me alive and going.
Maybe that's because I have such strict internal friendship rules, am so careful, am so doubting, that I don't really believe I have anywhere to turn. Whatever vows of friendship and support have been made at me in the past, my expectation of failure is greater than my trust.
So, I guess the circle is do I really have friends? Am I ignoring what exists? Or are my standards reasonable for a designation I want to have special meaning? Or do I set unreachable standards in the belief I ought to expect failure that is bound to happen?
I hate a paragraph of questions. I expect myself to be more self aware than that. But experience shows I don't know the answer. I'm at one end of a friendship spectrum or the other. I just don't know where I really stand.