Oh yes you can definitely have all the symptoms of AF and still be pregnant - thats why its so hard to tell sometimes because the symptoms are so similar.
The back cramping when you are pregnant is caused by the egg implanting into the uterus - it creates the same feeling you get when AF is coming. I was so convinced that AF was showing up the last time I was pregnant that I had protection on and started taking my regular pain killers! What a shock I was in for
All the best in your TTC efforts - 12yrs is a long time and I hope you get that BFP really soon