How to get the best tomato yield indoors?

I’ve been growing cherry tomatoes for years indoors with 10 L hydroponic buckets and a single light source. I’ve hit my yield ceiling now (~400 grams every 3-4 weeks) and I’m looking for advice to improve my output. My flat is in a cold country with no garden, so I have to keep my tomatoes indoors. I’ve setup a shelving unit in my living room which is my maximum space limit (vertically at least).

Any ideas? 💡