*Change is the only CONSTANT in life*
Please know that "Children" are very good at adapting to new circumstances, you have to focus on yourself and manage your anxiety/sadness/depression etc, please give yourself some time to get used to the change. Seek advice from other mothers who you think are managing a good balance between their professional responsibilities and family needs.
Once you know for sure that you need/want to make this change - going from PT work schedule to FT work routine, make plans for your day activities to go with your new routine. Please try and look at the positives of the "New Situation" as well.
Taking help from a family member (Grandma) is a good idea, hiring PT housekeeper for household chores/cleaning/laundry might be helpful in freeing up quality time to spend with your family. Let your husband be a part of this process and share some of the responsibilities with him as well.
Your children are getting older and will enjoy their new experiences at school, please try your best to maintain peace, be centered and practice being a guilt free happy parent each day.
PS: I used to work full time in the corporate world, now I have my own home based business providing educational services/teaching Art. I love working and contributing towards the financial success of my family. I am home for our son and enjoy this balanced lifestyle. My husband helps by taking our son to his activities and I have a PT housekeeper to help me with chores, so I have quality time to spend with our son and make my business successful.
Hope this helps.
N.