You're doing ok. Continue to work till 65. By the time you're 65, your home loan would be paid off. Also choose the Enhanced CPF life scheme. You and wife will get $3500 in total every month. This should be enough as you just need to spend on food and utilities. Don't own a car when you retire. Any contributions from your children would be a bonus. It is not difficult to retire as long as you:

1. Own your home outright with no loan so that you don't need to pay rent when you no longer work.

2. Choose the CPF Life scheme which gives you $1750 pm until you die.

3. Have good children who give you some money every month until you die.

4. Don't have bad habits such as drinking, gambling, smoking, womanizing, overspending, etc.