Getting your plants to "stretch" doesn't really mean bigger plants, just taller and more spindly growth and where there is a bigger distances between the nodes, with corresponding stretched and fluffy flowers. Plants growing in full sun with a gazillion watts will grow bigger and faster than under a 400 watt LED light indoors. Have patience with your seedling, she is just a slow starter and try and resist temptation into trying to get her growing faster by bombarding her with nutrients of any sort. Hope this helps,... Organoman.