Maybe the 3rd commandment has been differently interpreted by different people. I sort of took it to mean, don't call yourself a Christian if you're not. That's in vain. And so I took offense, because I truly DO believe I'm a Christian, just one who struggles with some weaknesses and issues and who truly does desire God's help.
Purpose of my writing here is not to insult you.
Also, my opinion if you are believer or not should not matter to you, for that won't change anything in your life, and you know some things have to be changed.
I saw something that it seems you don't see (as you don't really see/accept many excellent comments/advise from other people on this tread), and I just tried to tell you honestly, in order to help you seeing things from different angles, to face some of your own issues (that have nothing to do with God or you as a believer).
I also believe I'm a Christian (I believe in God, I'm honest, do no harm to people around me, am not cheater, am not false, etc.)
And yes, many of us have different interpretation of "God's rules".
E.g. I read Bible once, accepted those things things from it I could accept (according to my nature) and am obeying those same parts.
I don't go to church every Sunday, for I don't need church to be close to God.
Also, I despise people making sins 6 days, then going to the church on Sunday to beg for forgiveness, and so 'forgiven and clean' they feel recharged to sin again from Monday on, till next Sunday, and so on, in circles.
I try to be a GOOD person, and sin toward people as little as possible.
Also, regarding sex;
I am convinced that God will not punish me because I love someone and have sex with him before marriage, and I'm honest with that person, and we probe each other every way before saying 'yes, till the death...'
And I would sin if I lied/mislead, firstly myself, then people around me.
I am made with some characteristics that make me ME; breaking them by force would make quite another person of me then I am made for. And I don't think God's wish is to break me and make me unhappy.
At least, that is God I believe in.
So, now you know my beliefs (a little part of them though) and you might say that I'm not a Christian.
It won't hurt me.
For I'm pleased with where I am regarding this part of my life...
I found a proper measure of faith to be lived in my heart that is not burden but pure joy.
I do wish to achieve perfection--where my actions are totally in line with my beliefs.
Nothing wrong with that... so far you don't take it as opsession and ruin some nice things in life because of a picture of THAT perfection in your head made just by yourself and nobody else.
And mind can be very misleading...
I'm working on it, though, and asking for God's help.
God WILL help you.
IF you help yourself!
You can be drowning under the water and ask God for help, not swimming and not doing anything but waiting for Him to save you.
Would He help you and you won't be drowned?
NOT if you don't try to swim!
(One of interpretation of the 3rd Commandment, too, btw).
He won't help you with your daughter IF you just sit down and ask him for help, but not exploring and finding ways, persistently till you find them, to get back your daughter to 'old good values'...
The same with relationship.
He won't help you to have "a Christian marriage" IF you start with people they don't share those beliefs, moreover IF you start relationship with sex then you beat yourself trying to go back, and that repeats again and again in your life.
I mean, all of us make some mistakes, this kind or the other, but don't you think it's high time, at your age (I mean you are not 20 that you know little), to make IRREVOCABLE decision what you want to be and with whom?
Decision that will make YOU happy and pleased with yourself.
Once decision is made, don't think, analyze or go back and forth, in doubts, being torn, but live that decision YOU made for YOUR own peace of mind.
but when you can say it and not feel grieved that you disappointed God, and you lose your desire to do better next time, I think there's a bigger underlying problem.
Underlying problem is also that you can always, and for anything, find reasons you "disappointed God".
IF you program your mind thinking that way...
Be careful.
Misleading mind doesn't announce when crossing that subtle line that's dividing us from insanity... or from being unreasonable at the best...