Doing my first portrait shoot next weekend.

I normally do bird and real estate photography. I'm trying to expand my horizon and do portrait. I'm using a Canon 5DS-R, Yongnuo flash trigger , Canon 580EX II,2 small LED Continuous light panel, 1 Light stand with a see-through umbrella. Normally I wouldn't be concern with this setup if it was for just flash filling outside but I'm shooting inside a client's apartment. I'm sure I have enough light but I feel uneasy. I like to be over prepared when I go out and shoot. When I shoot real estate, I can always do HDR and get away with a lot but shooting portrait is a very different for me. Why do I feel like I don't have enough light ?

One flash is plenty of light for this situation.

When i shoot portraits in a home, i just use my flash/octabox as a fill light coming from the direction of window light with a possible white reflector for bounce on the opposite side from the light to fill. This helps keep the ISO low as unless you are night next to the window, there may not be enough light.
Some times you can get away with flash bounce off a wall or ceiling. Keep in mind you may want a reflector to add some more fill into their eyes if bouncing, but just see how it goes.
You can use window as back lighting as well and fill in with the flash, making a high key image.

Also consider doing some low key. A grid on your flash or just zooming the head in may help in this situation to control the light. Just use z smaller aperture and let the back fade to black.

Add a cto gel to the lcd panel and shine it at a table lamp in the scene, then light the person with flash for a nice mix of light and colors.

Micro5797 wrote in post #18037912
One flash is plenty of light for this situation.

When i shoot portraits in a home, i just use my flash/octabox as a fill light coming from the direction of window light with a possible white reflector for bounce on the opposite side from the light to fill. This helps keep the ISO low as unless you are night next to the window, there may not be enough light.
Some times you can get away with flash bounce off a wall or ceiling. Keep in mind you may want a reflector to add some more fill into their eyes if bouncing, but just see how it goes.
You can use window as back lighting as well and fill in with the flash, making a high key image.

Also consider doing some low key. A grid on your flash or just zooming the head in may help in this situation to control the light. Just use z smaller aperture and let the back fade to black.

Add a cto gel to the lcd panel and shine it at a table lamp in the scene, then light the person with flash for a nice mix of light and colors.

Thank you for your suggestion. I will have access to a big window with enough ambient light so I was thinking of just using the umbrella to fill flash. I don't have any reflector or assistant to help me hold it in place. I'm a 1 man operations. I do have 2 Yuongno 600ex on the way but they won't be available for the shoot. I do like the idea of bouncing the led light on a table.

1 light is all you need
http://photography.tut​splus.com …nly-one-light--photo-3313

limiting yourself to 1 light will let you focus on composition, posing, and interaction with your subject.

there seems to be nothing that will annoy subjects more quickly than a photographer fussing with a complicated light setup