Plants need macro-nutrients (nitrogen, phosphorus, potassium; called as NPK) and an assortment of micro-nutrients, amount and importance of which vary from plant to plant. One of the most nutritious and easy to obtain organic fertilizer for home gardens is compost. Compost is in general a balanced fertilizer, i.e., it has each of the three macro-nutrients in good quantities, but its composition varies based on the composition of inputs to be composted. For example, compost from kitchen waste would have different composition compared to, say, compost from cow manure. The advantage of compost from vegetarian kitchen waste is that it is neutral in acidity (pH), and over-application of it cannot harm plants. Over-application of most fertilizers, especially the inorganic ones, hurt plants, and may even cause decline and death. Perhaps the only better balanced organic fertilizer compared to compost from vegetarian kitchen waste is vermicompost. In vermicompost, the bigger and more complex organic molecules are further broken down to simpler forms compared to usual compost, making them relatively easier for absorption by plants. Its soft fluffy texture makes it an excellent medium for both retaining moisture and aerating the soil.
Based on the information provided in the question, you already have very good sources of fertilizers in your home. Those should be good enough for general houseplants. However, some exotic houseplants may require special care particular to the specific plants.
The principal sustenance of plants are light, water and air. Although nitrogen, phosphorus and potassium are called macro-nutrients, their amount actually required by a typical plant is minute. It is far easier to harm plants by over-application of fertilizers than by under-feeding them. Especially inorganic fertilizers can cause deaths of plants through over-application. Excess fertilizers can also change the pH of soil, reverting which may take considerable time or effort. In this aspect, compost of vegetable mass or vermicompost in fact is very close in character to the slowly decaying detritus in the undergrowth of forest, which is the environment from which the plants have evolved to obtain nutrients.
For the well-being of properly watered indoor plants, light is more important compared to fertilizers. The indoor lights may not be always adequate for plant growth.
Another thing, often paid less attention compared to fertilizers, is presence of bugs and pests in plants. Especially in home gardens, these small critters cause far more harm compared to lack of nutrients. In an organic garden, the availability of options in face of an onslaught of insects and harmful fungi are limited, and paying regular and close attention to the plants for the presence of pests and fungal diseases is often the most effective thing one can do. For indoor plants, insects are less likely to be a problem, but a humid environment indoors and insufficient light may cause the plants to be susceptible to fungal diseases.
In summary, apply compost and vermicompost from your in-house sources, you are quite likely to provide excess fertilizers to your plants, but cannot harm them by over-application of compost from vegetarian sources and vermicompost. However, check that your indoor plants receive adequate light, water them properly but do not over-water, and keep an eye out for symptoms of fungal diseases.
