Keep in mind that dd's needs when you're not there will be different from her needs when you are there. She'll know that the boobies aren't nearby, so if she needs to sleep more, her body will adjust to find a way to do that without them.
My dd (15 months) always goes to sleep easy as pie with her dad if I'm not here, for naps or bedtime (which is not often, but it makes it SO nice to know I can go out for a drink with the girls once in a while... a great while... sigh). If I'm here, though, it's gotta be me, which could give one the impression that if I wasn't here, she wouldn't be able to go to sleep at all. But she can.
When we first attempted nightweaning, if I would go to her and not nurse, she'd freak. But when dh went to her and I stayed TOTALLY out of the picture, she was fine, not a peep.
Here's my advice: don't spend the last few weeks you have with her trying to wean her at naptime, or change the routine, or anything. Throw yourself into it wholeheartedly. Give her the breast on demand, and go with her rhythms. When you go back to work, she'll adjust, she'll find a new way of falling back to sleep.
One more thought: does she have a lovey? If not, you could try to introduce one. My daughter's lovey is one of my shirts, specifically, any shirt that I've worn that day or the previous day. You could leave one of your well-worn shirts with her when you go to work, and she could snuggle that while she naps. I worked for a while, then I quit, but while I was working, my dd would carry around one of my tank tops all day with her.