Hi Prabha,
I can certainly understand how you would be exhausted. But with a little planning and a lot of consistency you can help him learn how to sleep better.
The first step is going to be teaching him to fall asleep on his own and that will mean no longer nursing or walking him to sleep. Nurse or walk him just until drowsy and then put him down to finish falling asleep on his own. Once he learns how to fall asleep on his own, then you will find things will start to improve from there.
He's probably going to protest when you do this. Depending on how you feel about crying, you can either just try to pat and shush him to see if he'll start to settle or if he gets really worked up, you can pick him up and help him to get drowsy again but then put him down. This may take several days or a couple of weeks for him to catch on, but the key here is to be consistent. Remember, you are teaching him a new skill. His protests or crying are not because he thinks you are being mean but because he's upset that things have change. But these changes are in his best interest to learn healthy sleep habits.
For a 14 month old, he doesn't really need to be feeding at night. So you may also want to start working on night weaning. Decide to limit his feedings to once or twice a night to start with and then also slowly feed him a lesser amount during these feedings. This will help his body become accustomed to not feeding all night long. When you find he starts to slow with his sucking, then gently unlatch him and let him fall asleep on his own. Again, he may protest this and become more awake again, but this is where you will need to be consistent and firm with him that he needs to go to sleep without using you as his pacifier.
He's napping 5 hours during the day mostly because he's not getting enough sleep at night. You'll need to work on cutting out the evening nap, because that's really when he should be going to bed for the night. Here is the recommend toddler schedule:
http://www.babysleepsite.com/s…..-schedule/
I would also recommend that you read through this series of posts about sleep training for ideas and tips on how to create your own sleep training plan.
http://www.babysleepsite.com/s…..es-part-1/
Hope this helps. Keep us posted on how it's going.