Im not quite sure why you were advised to exclusively express, because nothing stimulates breast milk production like a baby does!
firstly, you are doing great
im sorry things have been tough, but i am positive that with plenty of support and determination you will be able to get your little one back to the breast. The fact that she is latching on and feeding well occasionally is very encouraging
Something you could try, which will probably be quite effective, is stopping giving EBM from bottles altogether, instead giving it via a syringe. You're right in saying that she is probably getting a little lazy so if you stop the bottles altogether now, she hopefully will soon forget all about them and come back to the breast. Giving supplemental feeds via spoon or syringe is time consuming but it will be worth it! It may take a little while, and you will have to be very determined, but it might just work. I am tempted to say go cold turkey completely on the bottles for a day and see how she goes on the breast and the syringe. The longer she has the bottles, the more difficult it will be to get her back to the breast. Its really important that you keep your supply up by putting her to the breast as much as possible, pumping as much as you can and making sure you are eating and drinking plenty.
Other ways to encourage your daughter back to the breast are as follows:
1. Lots of skin to skin contact. Make the breast readily available but let her come to it in her own time.
2. squeeze a little bit of milk out onto the nipple before a feed to "entice" her to latch and stay latched.
3. Encourage milk let-down before you latch her on - that way there is no delay between baby latching and getting milk. start pumping until you feel your milk let-down and then get her straight on there!
4. Wear your baby in a sling - there's nothing like being in almost constant contact with mum to encourage breastfeeding.
Have you ever heard of SNS (supplemental nursing system)? Its a way of supplementing feeds without a bottle. Its like a little tube that goes from a unit to your breast, so the baby can latch on and feed normally but receive a top-up to the feed (be it EBM or formula). This might be worth a try. You should be able to find a way of obtaining one through La Leche League, most towns have a local LLL group that meets once a month and the LLL Leader who runs it will have contacts for things like that. This is usually something that is used when a baby needs formula top-ups for whatever reason, seeing as you are producing enough milk on your own it shouldnt be necessary in your case.