Another 30 Day Shredder here. If you are serious and want to lose weight you will lose weight and get fitwith 30 day Shred and what's more important it'll give you tangible structure and I personally find Jillian really motivating. It's often the gentle/ad hoc work outs that I ended up ditching as there was less accountability. Truth is: if you want to shift weight and feel fit, it will take something. I used it post partum and although it was hard to start the results kept me going. I had a colicky reluctant napper too so the 27 minute workout daily was perfect for me and let's face it, at 6 weeks post partum when I started I was pretty out of shape.
To avoid pitfalls of losing motivation:
Take pictures if yourself - front, back, side - preferably in underwear or skimpy workout clothes. Measure your waist, bum, thighs, arms. You may be severely displeased with what you see. Use that as a motivator.
After 10 days - repeat this. I guarantee you that the results will shock you. Positively.  this will help you stay on track. Do the same at 20 days and at the end. It's easy to not appreciate your own hard work or not notice the results so it's crucial you monitor it yourself.
My diet was controlled via MyFitnessPal with calorie goals. I'd say I stuck to my goal 70% of the time with a 3 week break where I indulged but trained all the time so I didn't gain any weight.
Chuck 30 day Shred in google and you'll see that people have managed this with some great results.
After completing the 30 days and shedding 10 lbs I just continued with 4-5 and then later 3-4 workouts a week. DD is 9 months and I've trained from 6 week post partum. Rain or shine, child naps in the morning, I train. DP knows that it is my personal goal and priority so at weekends/evenings he deals with DD whenever I need to train apart from his normal share of parental duties. Keeps me sane and present and I'm back to my pre baby weight. Not mentioning that DD is 10 kgs so I appreciate the strength and stamina I built up over time.
You can do this.
Ps. Just to put my money where my mouth is... 
These are my before and after - start and 14 weeks after. Difference is
70 kgs on the first one, 62 kgs on the second. I'm lighter than that now but I'm sharing this as it's a tangible timeline. If you start tomorrow by end of March you'll be looking and feeling fantastic.
Pps. Heard excellent things about Joe Wicks programmes too and a friend got similar results with him so I can indirectly recommend it to but as with Jillian - consistency is key. A little every day is better than a lot once a week.