Birgit,
The bulbs that you purchased are 13 Watt and 2700K Color Temperature. The product details on our site indicate the Lumen output at: Lumens: 810 - which is the strength of the light in your terms. Being only 2700K this is a very warm light output. We would suggest that you check inside of the actual can in your ceiling to ensure that the wattage of the bulb is compatible with the fixure and ballast. You may be able to use a higher wattage bulb which will give you more light. We may also suggest an LED replacement which can give you much brighter light output. If you wish to return the bulbs for a different type simply reach out to customer service: support@lightstoreusa.com Thanks!