I need sleep help

My 7 month old has NEVER slept through the night. EVER. I am exhausted, he’s tired, my husband is tired ....i don’t know what I’m doing wrong! He goes to bed at 7-730 every night and he normally goes right to bed and then at 12-1 he starts waking constantly, like every 4-5 minutes until I have to get up for work at 6. We’ve tried keeping him up later, cereal in his last bottle, sound machine, binky, blankets, letting him cry a little bit (2-5 minutes) to see if he will fall back asleep .....I just can’t understand why he’s not resting. I’m SO tired I’ve been falling asleep at work and my husband is cranky. Our friends babies have been sleeping through the night for months now and I’m just wondering if it’s my fault somehow?