lyannas:

I had taken “if I look back I am lost” to mean a willful erasure of the past, and a refusal to examine it. Dany repeats it 13 times over the course of the books, always in situations where she is uncomfortable or unsure of herself. She first thinks it when Mirri Maz Duur recalls the “birth” of Dany’s child:

“Monstrous,” Mirri Maz Duur finished for him. The knight was a powerful man, yet Dany understood in that moment that the maegi was stronger, and crueler, and infinitely more dangerous. “Twisted. I drew him forth myself. He was scaled like a lizard, blind, with the stub of a tail and small leather wings like the wings of a bat. When I touched him, the flesh sloughed off the bone, and inside he was full of graveworms and the stink of corruption. He had been dead for years.”

Darkness, Dany thought. The terrible darkness sweeping up behind to devour her. If she looked back she was lost. “My son was alive and strong when Ser Jorah carried me into this tent,” she said. “I could feel him kicking, fighting to be born.”

Dany doesn’t allow herself to remember exactly what happened in the tent. She thinks only of the darkness, then pushes past it, unwilling to face the details of it.

This willful erasure/forgetfulness becomes more obvious here, where Mirri Maz Duur blatantly points out that Daenerys lies to herself (to the point to where Dany believes her own lies):

Ser Jorah had killed her son, Dany knew. He had done what he did for love and loyalty, yet he had carried her into a place no living man should go and fed her baby to the darkness. He knew it too; the grey face, the hollow eyes, the limp. “The shadows have touched you too, Ser Jorah,” she told him. The knight made no reply. Dany turned to the godswife. “You warned me that only death could pay for life. I thought you meant the horse.”

“No,” Mirri Maz Duur said. “That was a lie you told yourself. You knew the price.”

Had she? Had she? If I look back I am lost. “The price was paid,” Dany said. “The horse, my child, Quaro and Qotho, Haggo and Cohollo. The price was paid and paid and paid.” She rose from her cushions. “Where is Khal Drogo? Show him to me, godswife, maegi, bloodmage, whatever you are. Show me Khal Drogo. Show me what I bought with my son’s life.”

Again and again, Dany repeats “If I look back I am lost”. When she learns of Eroeh’s fate (a child, who was raped and killed by the dothraki) Dany repeats this mantra and does not allow herself to dwell on what happened or react emotionally to it (AGoT, Daenerys IX). She repeats it immediately after looking up a catatonic Drogo and calling him her “sun-and-stars” (AGoT, Daenerys IX). It becomes a knee-jerk reaction to things that she simply does not want to think about:

She could feel the eyes of the khalasar on her as she entered her tent. The Dothraki were muttering and giving her strange sideways looks from the corners of their dark almond eyes. They thought her mad, Dany realized. Perhaps she was. She would know soon enough. If I look back I am lost.

“Aggo,” Dany called, paying no heed to Jhogo’s words. If I look back I am lost.

If I look back I am lost, Dany told herself the next morning as she entered Astapor through the harbor gates. She dared not remind herself how small and insignificant her following truly was, or she would lose all courage.

Finally, in ADWD, Dany realizes what exactly she’s been doing to herself each time she said those words:

If I look back, I am doomed, Dany told herself … but how could she not look back? I should have seen it coming. Was I so blind, or did I close my eyes willfully, so I would not have to see the price of power?

For the first time, she debated with the past. She wondered if she was truly ignorant or willfully so. This moment does not last, however. She slips back into ignoring the past, forcing herself to see what she wants to see:

Much of the talk about the table was of the matches to be fought upon the morrow. Barsena Blackhair was going to face a boar, his tusks against her dagger. Khrazz was fighting, as was the Spotted Cat. And in the day’s final pairing, Goghor the Giant would go against Belaquo Bonebreaker. One would be dead before the sun went down. No queen has clean hands, Dany told herself. She thought of Doreah, of Quaro, of Eroeh … of a little girl she had never met, whose name had been Hazzea. Better a few should die in the pit than thousands at the gates. This is the price of peace, I pay it willingly. If I look back, I am lost.

She cannot and will not dwell on the tragedies that have happened, that she has brought on, and that she had endured. She constantly pushes these thoughts away. Those seven words are a coping mechanism, and a powerful one. They keep her moving forward past her mental hurdles– at great cost to herself, and others, unfortunately.

I’d like to add that it is precisely because of how often she does this that I believe that Dany forced herself to love Drogo and the dothraki way of life. Dany finds it much easier to lie to herself about the bad things that have happened, if she cannot forget about them completely.