just let them know that you love them and regardless of the amount of time you have to spend with them make it quality time. I'd have to know respective ages to give any advice on activities.
often parents spend lots of money on their kids thinking that will make them happy but it isn't what they really want they just want to know that their parents love them and want to spend time with them, take them on holiday or a special day trip somewhere. you don't need to spend a lot my kids like it when we go to a beach or a woodland park with a river in it and play in the water together.
i don't how old are your kids.
But I believe you need to know what they are playing, what they are watching. If they are kids, try to make some buns with them, and play boardgame with them.
For teenage, I suggest to play video games and computer games with them.
The best way to be happy with kids are playing with them.
If you think most of their games are so childish and you are not interested, you can try making cookies, black jack(I taught my very little brother to count numbers)..
buying things for them makes them happy, but you should really spend time with them.(but don't embarrass them). take them to the movies,parks, a carnival. Just don't let them take over you.
How do you know that they're unhappy ? Give your self a break your probabaly doing all that you can already. So long as you love your children, listen to them and spend quality time with them then your ok.
Doesn't matter how much time u give to 'em but make sure the time spent together must be special n magical. Talk to them ask what happening in school/college, take them out atleast once a fortnite, play with them use these words oftenly like I miss u kids at work, I love u etc. This will help.
just be with them as much as possible. It is the family love setting they crave not the things and stuff. Cuddles and story times..lay off the TV and video games. The stuff will only seperate you further. If possible have them help you in the kitchen. Simple things make all the difference. A few minutes of tickle wrestle time is great. BUt remember to keep in with the house rules too. Kids also desire order, routine and disipline. So don't stray too far.
Make sure the time you spend with them is just that family time. Don't answer the phone don't do any work of any kind. Remember it's not always about quantity but quality is what they will remember!
If that doesn't work than you could look for another Job.