To bring your Ph up a bit, add dolomite or garden lime to the soil. About a handful to the square yard. This will help with the next suggestion.

Legumes are a plant which take nitrogen from the air and fix it to their root systems. Examples are peas and beans. If you lime the beds, and grow a crop of legumes, then when the crop is lush and just about to flower, you dig it all back into the soil. This will increase the nitrogen levels in the soil as well as increasing the organic matter.

Potassium can be added with a side dressing of sulphate of potash at the same time as you sow and then again as you dig in the "green manure" crop.

Also, blood meal is very high in nitrogen but has no P or K,. So a mix of blood meal and sulphate of potash would work to balance the soil as an organic quick fix.

If you don't mind using chemical fertilizers, there are plenty of granulated products which have specific ratios you could use.

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The secret is the soil.

you can but 0 0 60 fertilizer at Southern States, for very cheap. Its basically just pure potash- not Nitrogen or potassium. Green manures such as rotting grass will raise nitrogen. Too much nitrogen will produce more leaves and less fruit/vegtables.