Do you find any part of your life enjoyable, or is it all a bit dull and no fun? I ask as I wonder if you are still depressed with everything, or it is just that small children are rather tedious (as the remedy for these two are different).
If you have no enthusiasm for anything, and don't really enjoy anything and feel flat, then you may still be depressed, so visit the GP.
If you like hanging out with your husband, find your work quite stimulating and so forth- then I'd work on how you think about your role with the children.
You have, to a large extent, done the super hard slog of tiny children, but they aren't quite yet independent enough for you to feel the benefits. I remember having a Sunday afternoon when the children were just slightly older, about 7 and 5 and they were both off playing independently, one on the tablet, one outside with friends- for a couple of hours. I sat and read the paper for those two hours and marveled at how I was getting my life back (or at least the life in which I had a small amount of time for me).
This will happen as they get older naturally- but also encourage your children not to depend on you as an entertainer. If you go to the beach, watch them a bit around water but you could also take them to a nice playpark and get your book out. You don't need to be constantly entertaining them- think of yourself as a facilitator for their lives, not their entertainer. The fact they are near in age hugely helps with this. Let them build stuff, entertain each other, take them to classes where others entertain them (e.g. Brownies, Scouts, judo or whatever). Be super friendly so others invite them around a lot (and do the odd bit in return). I don't entertain my children now they are a bit older (think 11 and 13 ish), I facilitate their social lives and take them places! Then I put my feet up and read MN or a good book or work or whatever.
If you don't have a job outside the home, definitely consider that as an option- just to socialise, get out of the house, it's associated with less depression.
Don't compare yourself to anyone else either, I don't love days out, I love pottering at home- so I let my husband take charge of days out and sometimes I stay in! I don't like playing with Lego, so I don't. I do lots of other things I do like with the children, though, like talking, watching series together (that we choose), snuggles in the morning, reading, doing homework together.There's more than one way of being a parent and I think you need to rebalance it so you do more activities you enjoy yourself, and incorporate that into your parenting. This will happen more naturally as they age, but you can speed it up!