It is totally normal, and totally exhausting 
Mine was similar - he fed for 8 hours straight one day. He cluster fed in the evenings from about two weeks to about four months.
It’s called cluster feeding and it’s very normal as they stimulate more milk supply. They seem to go through short intense bursts of it —> boost the milk —> gets a bit better.
I know you’re shattered and you aren’t keen on cosleeping. Neither was I, but in the end it was the only thing that meant I could at least lay down and doze.
Look up how to consleep safely (no covers at their level etc) and give it a go. If you can lie on your side, and feed, you can doze. It’s not deep sleep but it will get you through.
Your partner also needs to make sure they are giving you a ‘block’ of sleep once or twice a week, where they take the baby for a few hours and you sleep. Please do this. Even if it means a bottle.
A word of advice for someone who nearly lost her mind with sleep deprivation (being woken hourly for 18m takes its toll.)
- There’s very little you can do to make a baby sleep. You can and should get a routine of light days and dark quiet nights. You can take them out for a ride in the pram to nap etc. But whether they sleep well seems to be inbuilt. You get good sleepers and you get bad. Yours so far seems pretty normal. Anyway, it’s a waste of effort trying to change their sleeping ability - all you can do is develop coping strategies. That really is vital because it’s something you can control. So partner MUST take baby 2x a week minimum and let you sleep for a few hours, for example.
- Sleep changes constantly at this age. Again, see point 1, and accept there’s bugger all you can do to change it. Up to about 5-6m their sleep will change almost week to week. You’ll go through ok weeks and hellish weeks. And NOTHING you do will change how they sleep. You can ONLY change how you react to it and cope with it.
One last thing: breastfeeding is wonderful. I bfd my son for 18m. At the same time, a Mum who is about to crack with sleep deprivation is far worse than giving the odd bottle. Formula isn’t poison. If I’m ever lucky enough to have another I will be mix feeding with a bottle a day from the off, because being chained to a baby who fed constantly and woke constantly nearly broke me.
If you want to give a bottle, so you can sleep and your partner can do a night feed or an evening feed, then do, without a shred of guilt. There’s far too much guilting of mums for all this - do what gets you through. 