Aww hun, is there any way you can lower the base of the cot and take off 1 side? so she can a little more easily get out?
Maybe she's ready for a big girl bed?
DD1 was 15mths when DD2 was born and she was sleeping on a matress on the floor when we stayed at our new house, then when we moved we eventually got her a bed and to be honest she sleeps better in that now than in the cot.

You weren't to know she was out hun, don't beat yourself up..