Greywolf73,
I had the same experience you had. We learned to write cursive in 2nd grade, and my teacher was convinced that being left-handed was somehow wrong, so she was always taking the pencil out of my left hand and putting it in my right, telling me that my handwriting would be “so much better” if I would just use my right hand. What a crock of crap that was; I couldn’t write with my right hand at all. So I’d switch back, and I got lousy grades for penmanship all year, just because I was left-handed. My writing was actually quite a bit better than some of the other right-handed students in the class, but since I was doing it “wrong,” bad grades were what I got. Of course I was too little to realize at the time that she was the one who was wrong. It would have saved a lot of stress if it had occurred to me to tell my parents what was happening; as it was my mother was upset with me for not getting perfect grades. It was very frustrating, and of course in that situation it was impossible to improve the grade, I just didn’t know it. When I think back on it, it was amazing how ignorant that teacher was; this was not the only thing she did that was not in the best interest of her students, but she really didn’t know any better.
I started off writing with my right hand, so never experienced anyone trying to teach me to write ‘properly’. I’d just practice writing with my left on my own time.
My father (who’s in his mid-50’s) is a lefty: he didn’t go through the whole ‘you must write with the right hand’ deal mostly because his Mom was a teacher (one room school house, etc., etc.) and basically bullied the school into not even attempting to merely think about the slightest attempt to teach Dad to write with his right hand. 
(Go grandma!)
I got taught to write with my right hand by a nun who had been pulled out of retirement because of a “shortage of teachers” (Later we found out that it was a shortage of teachers willing to be paid nothing, but that’s beside the point). She was from a time when teachers could hit kids and nobody (at least no good catholic kids) wrote with their left hands.
Anyway, it royally screwed up my handwriting. Now I can write about as well with either hand, but that’s not because I’m ambidexterous, it’s because I write like crap. It doesn’t matter which hand I use.
My occupational therapist sister tells me that trying to re-learn how to write lefty properly at this stage of the game would probably do more harm than good, so I guess I’m stuck with it.
My first grade teacher attempted to make me write with my right hand by standing behind me and holding my left hand behind my back. :eek: I came home from school one day with a sore left arm. I told my folks what the teacher was doing to me, which did not sit well with my left-handed father. The next day, he went to the principal, who was not pleased with what was happening either. The holding my left hand behind my back stopped, but she made no effort to teach me how to hold a pencil, so I figured it all out on my own.