It makes me sad to see that you have magnified a problem, that can be managed, into a catastrophe that is making you desperately unhappy. So, let us take this complicated situation apart, and look at each piece. Better to have correct information than to assume the worst and worry constantly.
Having one testis is of no great importance. One is all that is needed. If it was surgically brought down in time, it is probably producing sperm. This can be tested by a urological doctor, who can have a sample of your ejaculate examined in a laboratory for a sperm count.
Being raped when younger is a separate problem that probably did give you an inferiority complex, and make you insecure about your manhood. That may be why you kept away from women for some time. If your feelings about yourself as a man are still troubling, a psychologist may help you just by talking the situation over, so that you see it in a more realistic light.
If the girl you love is willing to marry you, then she must love you, and that is wonderful and can help you overcome many of your problems.
EVERY young man has a problem with premature ejaculation when he first is learning how to love a woman. It is complicated, and takes time to learn, and practice. Nervousness and anxiety are the enemies of love-making. Here, the love between you, plus patience and talking together, can help a lot. What a woman needs to satisfy her comes less from the penis of the man that from his words of love, his tenderness, his affection. Ask her if this is true, and best of luck.