Baby sleep

My baby is 5months old but have yet to sttn. From 1month plus - 3months he will sleep a first 4-5 hours cycle then wakes up every 2 hours. 3 months plus onwards, he wakes up every 2 hours. I thought he was close to the 4 months sleep regression. But it didn’t improved from there. Only surprise is once he slept a 6 hours straight (after 3months plus old). During 1-3 months, he slept once 9 hours & 7 hours. These 3 occasion was the only time we could have proper rest. Now I’m back at work, waking up every hour is tiring. Does any parents know if there’s any reason behind this or how i could improve? I doubt is not enough milk, I feel it’s more like a habit of waking up every 2 hours for latching. As he either latch or rocked to sleep