I have a 14month gap. They are now 22 months and 8 months. They are polar opposites. The baby is fantastic in the day but is a terrible sleeper and wakes anywhere between 3-10 times a night. The toddler is a fucking nightmare all day but sleeps 12 hours straight through at night.
The eldest constantly terrorises the baby and cannot be left alone for 2 mins.
They will hopefully become best friends and im hoping it'll be easier when the baby is mobile or even tries to sit unaided!
As others have said, routine is the key here. Also going out everyday helps even if it's just to stroll around tesco or for a walk.
Be kind to yourself. Sneak in any rest you can, even if it's just 2 minutes.
Grab ANY help offered with both hands from friends or family or anyone! We have had no offers of help yet. Both Grandparents are young, fit and retired but haven't so much as offered to babysit for 10 mins whilst I pop to the shop.
I've learnt to lower my standards. Don't expect too much of yourself in the first few months. Plan to tackle only one thing per day (or nothing at all).
Once I accepted that the house is going to be a cluttery mess most of the time and that I can't go out with perfect hair and makeup anymore life became easier!