Hello R.,
Caring for 2 children under the age of 3 can be tiring, hope you have a daily routine that included taking care of "YOU" first, so you have enough to give back to them, I mean making a little time for exercise, meditation, talking to friends ( for adult conversation) etc.
Please seek help and talk to a family therapist if you need to.
Having a routine for your son, that includes outdoor active play time, social play- play dates, art/ craft, dress up/pretend play, reading time, TV time, library trips.. can help with the flow of the week. Local bookstores have free story time for kids his age and so does the library.
If he does not go to pre-school yet, may be it is time for you to explore that option. If money is an issue, find a state funded, free/subsidized program you can enroll him in.
Please research Ages and Stages milestones/ behavior norms etc for 3-4 year old. Knowledge is Power, may be in the meantime you need to take time to help yourself be more centered and acknowledge that you are not a super woman, Parenting is NOT a perfect process, it is on-going learning experience.
Staying home, a financially responsible decision on your part, you should be proud of yourself, it is NOT for everyone, be honest with yourself and figure out a solution that works best for your family.
Regroup your thoughts and choose to live each day with a positive attitude, take care of yourself so you'll be a happier mother who is glad/thankful to be home for her family. Enjoy this time of wonder, it will never come back.
Find a local Mom's group you can join, being part of the community will help you I think.