Hi,
I have lived with depression all my life. From around age 17 to 55. It's bloody challenging but it can be done.
My own recipe for living with it is:
Take frequent breaks from it. If you feel better when you go for a walk/run or when you watch a comedy or cuddle an animal or DC etc, do these things often. Make a list of things that give you a 5-10 minute break from feeling rough and ensure you do as many of them as you can each day. These don't make you feel better afterwards but they do press pause. Very valuable.
Use CBT techniques to check in with yourself. Notice small victories. Turn damaging thoughts around by having some sane questions on standby. E.g. if you start getting obsessed with: My business is going to fail, let Sane Voice take over and say: Businesses are very challenging in their early months and its extremely common for them not to make a profit for three years. It's normal to have hiccups and learn from mistakes. I picked this business because I saw a gap in the market and I know it can fit in with me being a mum. I can make it work. But maybe I'd feel more confident if I went on a marketing/bookkeeping course/started small/set aside 30mins each night once DC's in bed to develop the website. Talk to yourself in a nice kind, sane voice. Practise challenging the depressive voice. I find that so helpful.
Journal. In your journal make a list each day of what you have done that day that was worthwhile, however tiny: (I hung out the washing, I let MiL talk at me so she didn't feel lonely, I had a lovely giggly cuddle with DS that he loved and so did I, I searched online for baby clothes supplier etc. That will help you recognise that you are needed and valued in the world. Suicide is not an option. Add a gratitude/blessings list as well. Just three things each day that you are glad about.
Book small and large things in your near and distant future that you look forward to. Anything from taking DS to see Santa tin Lapland when he's old enough to having a quiet drink with your partner tonight when he gets in from work.
Life is long. You have massive stresses right now. It's understandable you feel down. And you are right to be watchful that it doesn't tip into another depression. But you are doing loads of things right already. You are talking about it (I never did) You are focusing on how much you adore being with your DS. (That will help.) You are acknowledging what is genuinely challenging about life at the moment. (This helps give a fair perspective on life.)
In time you will be in your own place. Your business will be up and running. Or you will have chosen another direction. Your DS will be happy and settled and so will you.
I truly am a very happy person who has a battle with lifelong depression. I hate it. I get furious with it for interrupting and holding me back in so much of my life, but in between bouts of it, I think I enjoy life more than most, because I've trained myself to really really appreciate the small things in life. The joy of a snuggle with the cat or a half hour comedy, or the sound of DC laughing in another room or the glimpse of a rare bird in our garden. I take massive pleasure in the every day. And I put massive effort into making sure there is always something to look forward to - an outing, a holiday, an interesting work project. I know a lot of non-depressives who are much sourer and more cynical about life than I am.