hi froglegs - I'm 6 weeks further on than you, in that my DS is 10 weeks old now - but he fed pretty much constantly for the first 8 weeks. even with a formula or EBM 'top up', the longest he would sleep would be 2 hours, than he was up wanting fed again. most nights from week 3-week 8, we were lucky if he'd go down before 11, then he'd be up at 1, and cluster feed all night and day. The only time he wasn't feeding was when I took him out for a walk for an hour every lunchtime, so I (and my nipples) could have a rest. Also, on a weekend, my DP would take him for 2 hours, put him in a sling, and let me sleep. without that, DS may not have made it this far...
However, after his immunisations (this is coincidence I'm sure!), he had a bit of a fever, so I gave him some calpol, and he slept for 4 hours! and since then he's been feeding a lot less, and sleeping a lot more. I think the calpol maybe broke his 2 hour sleep cycle, or maybe the shock of immunisations scared the crap out of him, and made him sleep more? (more likely it was just going to happen then anyway)
He is still gaining weight at a ludicrous rate (6.5 kilos now, from 4 at birth), but at night he can sleep 10.30-2, 2.30-5, 5.30-9, then he's up for the day. it's lovely, and was worth persevering, but believe me, not a day went by that I didn't mutter 'formula' to my DP. and not a night feed went by that I wasn't sobbing hopelessly with a baby draining me dry. For me, it now seems like it was worth it to have those dreadful few weeks post birth to build up the supply of milk.
A friend of mine had a similar situation to me with a baby that never seemed satisfied, but she switched to mixed feeding after 2 weeks, then exclusively formula after 7 weeks. I saw her last week and she looks so so much happier - bf was not for her.
so long as a) baby is happy and healthy, and b) you are happy and healthy, the method of feeding is irrelevant. It may magically get better for you (like it luckily did for me), it might not - good luck, and I hope you are able to get a good night's sleep soon!