Help evaluating my daily activity?

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I'm trying to get some accurate numbers on my TDEE, but I feel flummoxed trying to figure out exactly how active am I? Sedentary? Lightly active? I'm worried I'm over-estimating or under-estimating my calories burned with exercise, and as a result not eating the right amount of calories.

Part of the problem is that because of my lifestyle, I'm not doing a lot of standardized exercise. I'm hoping if I list what my daily activity is like, some more experienced folks can help me figure out how to come to a reasonable guestimate of how many calories I'm burning.

1.) I have a desk job. I have a timer to remind me to get up and walk around the cubicle "block" every half hour, but at work I'm primarily sedentary.

2.) I have two dogs and no yard. I walk them 4 times a day. Typically the walks range from 10-20 minutes, moving at the fastest pace I can get two goofy boxers to go. I try to make the dinner time walk half an hour at least 4 times a week, but don't always manage it. So best case scenario, I'm getting 2 ten-minute walks a day and 2 fifteen-minute walks a day.

3.) I ride my bike to work. Sort of. I work at the top of a very steep hill. Going to work involves about 6 mins of brisk cycling on a mostly level surface. Then 4 minutes of spastic pedaling on a brutal upslope. Then 6 minutes of trudging alongside the bike to the top of hill. (My goal is to be able to ride my bike all the way up. Someday. In the future. Possibly.)

4.) I ride my bike home. Sort of. Going home is like 1 minute of WHEEEEEE! OHGODIMGOINGTODIE!!! down the hill. Then about 5 minutes of brisk pedaling on a level surface. Soooo ... I enter the round trip in my diary as 20 minutes of moderate cycling, but am I kidding myself? What the heck is this?

5.) I make the round trip twice a day, five days a week. I go up in the morning, home at lunch to walk dogs, then up again, then home.

In your best opinion, is this primarily a "sedentary" life or a "lightly active" life?

(I'm working on adding more, perhaps more easily quantifiable exercise, but I'd really like to figure out what I should be calculating my actual life as.)

If anyone can give me clue about this, I would really appreciate it.
Thanks!
~Red