So many potential areas to explore, it's great that you're open to trying. I think that being open is part of the battle. Here is a bit of a list on things currently working to improve things for us...
DH like you is on citilopram and it helps but isnt a magic cure. We work together on monitoring things that make a difference and things that don't.
At this time of year 20 mins daylight and fresh air is high on the essentials list. It can be sitting with a cup of tea in the garden but a walk also helps.
Avoiding caffeine after about 4pm, he has night kalms tablets which help with relaxing at bedtime - good sleep (harder with little ones) has an effect.
Eating small regular meals also helps regulate things as does not eating cheese after 8pm and nothing heavy in the run up to bedtime. Keeping hydrated and nourished seam like silly and obvious things but when running round after young DC it's easy to let this slip.
Taking the citilopram within the roughly the same hour everyday also helps.
Alcohol in moderation in the evening helps him unwind. After years of being uptight about alcohol he now has a glass of wine maybe 4 times a week (that's one medium/large glass 150mm sort of size). Occasionally he has 2 glasses but more than 2 and it has a negative knock on on his sleep and anxiety.
Writing down his worries and ranking them out of ten for severity, reviewing past anxieties to try and rationalise can help.
Busy tasks like doing the laundry, ironing, vacuuming - we have a list of jobs we work through, so even if it doesn't conquer the anxiety it moves life forwards gets essentials done and creates a nicer environment to be in. Being happy in the space you're in helps.
Slightly different scenario to your situation but I was a single parent to my eldest two when they were 1 and 3. Our local health centre did off peak gym/ swimming/ exercise classes with childcare so you could get a little bit of child free time.
As I get older I realise just how common anxiety is and how little we really talk about it. If you can find the strength to try some mum and tot/ baby groups you may find the company some support and even build your own support community.
Another thought is If you're in an area homestart operate, would you consider having a volunteer? If they are in your area, volunteers have received basic support training and come once a week for a few hours and can do things like go with you to baby groups so you don't need to go alone, or in some cases help you access services like counselling by going with you and the DC.