It gets easier. My DSs both woke at night - the first had feeds at 10pm (or thereabouts), 3am, and 6am for about 6 months, the second fed at 1am, 4am till over a year (has only just stopped waking for one feed at 4am at 15mths, tbh).
I didn't co-sleep, as I found that I couldn't get comfy in the bed with my LOs (worried about rolling on them, suffocating them etc.), but lots of people do co-sleep successfully, so might be worth posting another thread enquiring about that.
IMHE you have to discipline yourself to getting back to sleep asap once you've done a feed. They can faff about a take a while to settle, but tbh I found that often they would settle well after a feed. Is your LO warm/cool enough, dry/clean (nappy), getting enough milk at each feed (by 14 weeks I was definitely offering both breasts at each feed).
If you've only got the one baby, then definitely try to get your head down for a nap when your LO has a daytime sleep(s), and don't stress about housework etc. That can wait.
If she goes for a longer period of sleep from, say, 7pm-midnight, consider going to bed yourself by 8 or 9 every other day (at least) to make sure you're getting a longer block of sleep at night.
You could try expressing and getting your OH (assuming you are not doing this on your own) to give DD a bottle of EBM the first time she wakes up at night. You could have earplugs and ask your OH to wake you up for the second feed - when you hand over the earplugs and (s)he gets the chance for uninterrupted sleep.
Cut out tea and coffee after lunchtime each day, to make sure you can settle yourself back to sleep after feeds. Try to get out in the daytime to have some exercise and fresh air.
Rest assured that it does get easier. There is no denying that it can be really hard work keeping going - and babies are all different, so yours might suddenly start "going through" next month - or it could be months. However, you are giving your DD a fabulous start, and generally things get easier around 6mths once you start weaning her, and when she starts trying to sit up and shuffle about on her bottom (or whatever method she chooses to get about). Hope you have a good night