Shame Lata - it sounds exhausting. As you have said once the bad habit starts again you really are back to square one.
I am not sure of how the sleep sense sleep training works, so really can't comment on that technique.
I feel quite strongly about setting up a sleep routine early, because I feel parents really need adult time, and babies need to be in a pink or blue room somewhere sleeping.
My system works along the lines of dinner at about 17h30, play a bit, bath with mom around 18h30 - then dress for bed, and depending on the situation, she gets a warm bottle lying in my bed with me, and then when the bottle is finished or she no longer wants any more, I take her into her room, kiss her good night, pop her in to her cot, close the door and walk away.
The problem with the walking away is that on day 1, it usually results in a 60 - 90 minutes of my-head-is-going-to-explode-right-now-scream session. Baby eventually tires and goes to sleep - but mom is often climbing the walls after the first 15 minutes.
The key is not to go into the room unless the baby is actually dying.
Each day do the same routine, each day the minutes get less. Eventually baby can be put in the cot, door closed and baby goes to sleep.
The issue is consistency, and not going in to sooth baby, or to supply snacks, as that will only encourage baby to cry more as they will know eventually you will come. Even peaking in, or opening the door slightly puts you right back.
Sleep training - as all moms will attest is hard work,and requires a resolve of steel.
However within 5 - 7 days you should (barring any real life threatening issues) have a baby that goes to sleep, and you and DH can be sitting on the couch by 19h30 drinking a glass of wine and having an adult conversation.
I hope you get some sleep soon - I really feel for you. We have all been through it (though that does not make you feel any better right now.)