is this a lot of food

Well, it depends.  Is that a snack or your breakfast?  As a snack I'd say, about right.  As breakfast, probably not enough.

I'd strongly suggest tracking your calories (for at least a few days) to see how much you are eating.  You might not be eating enough, or, you might be eating too much.

I use

http://www.fitday.com

it's pretty cool, and easy to use once you get used to it. 

Doesn't sound like much to me...how does it break down into calories and macronutrient ratio?  Also, how much do you weigh (that right, I asked a girl how much she weighs), what time do you wake up, and do you train in the AM?  You've probably conditioned yourself to the small meals which is why you feel full so easily but that doesn't necessarily mean you are getting enough calories.  Final question...how much are you training?

I LOVE SUSHI!  White rice isn't the best thing in the world but it's not like I eat it every day.

So you wake up at 5:30-6:30 but don't eat anything until 10am...and you train then too?  An average low-fat fruit yogurt has about 150 calories and a medium pear has about 100 calories.  I'll assume you go to bed around 10pm and probably eat dinner by 8pm (just to make a point).  This would mean that you are giving your body ~250 calories to sustain, recover, and build for 14 hours (10pm-noon).  How's your training going...are you getting faster and stronger?  I'd guess not so much.  How could your body possibly get stronger without any building blocks?  If you were having trouble loosing weight before then I know exactly why...you weren't eating enough.  5-800calories below daily requirements is all you need to lose 1lb per week.  Restrict yourself much below that and your body will hold on to every ounce of fat it can and store more fat every chance it gets because it is in survival mode. 

I would suggest you eat at least 200 calories immediately after you wake up and then another 2-300 calories after you train.  Recovery nutrition is extremely important if you want to get the benefits your are working for from your training.  Do you have any idea how many colries you take in for an average day?

No problem.  If you are getting faster and stronger then things must be going okay overall.  The goal is to eat steadily all day long with specific things immediately before and after a workout for proper fueling and recovery.  You'll have to experiment with your morning meals to find something that you can convince yourself to eat on a regular basis.  I like Detour bars for a quick bite before my AM workouts.  They make a smal version that is 180 calories with a good mix of carbs and protein.  Maybe try a slice of bread with a tbsp of peanut butter, or a banana and peanut butter, or a small protein shake, or a bowl of whole grain cereal.  And then immediately after your workout it's important to have a recovery drink like Endurox.  Your muscles will be "thirsty" for carbs to replace glycogen so don't worry about the sugars...you need them after training.

I won;t try to talk you into using FitDay on a regular basis but you might try it for an average eating day to see about how many calories you are taking in and when...as well as your macro-nutrient ratio.  It would be helpful information for establishing a nutrition plan.