Yesterday when we took Kelli to the vet for her scratched eye, we were told that she's gained almost 2 pounds since her last visit.

She now weighs 10.3 pounds. Her weight has fluctuated since we got her. Ideally, she should weigh 5-6 pounds, according to the Dr. So I guess we're looking at her being 4-5 pounds overweight?
I will admit that we spoil her way too much. She gets alot of veggies, but most of the time we mix them in with her food (which we buy from the vet, supposed to be really good for her kidneys). But, she has gotten more than her fair share of table scraps which we're going to stop immediately. We know we're spoiling her and that we have to stop it, it'll be hard since she growls if we don't give her something when we eat, but we'll get over it, lol. I think she was fed ALOT of human food at her old home, which is why she acts that way when we eat. She was 9 pounds when we got her, we got her down to 8, now she's up to 10.3. We do NOT want her to gain anymore, we worry about her health.
Which leads to part one of my question--she's been gagging alot after getting worked up. If someone plays with her or she barks too hard/much, etc. she tends to cough and then gag to clear her throat. I read somewhere that it was just them kinda gasping for air and being scared when they couldn't take it in normally. I don't remember where I read that, but could this partially be due to her weight? Today I'm a little worried because she's making grunty noises in her sleep like her nose is stopped up, and when she gets worked up (ie. from barking too much) she sounds like she has congestion in her throat and she acts like she's trying to clear it. Hard to explain. I'm just wondering if the heavier they are, the bigger this is a problem.
AND, my other question is about diet and exercise. We feed Kelli twice a day, morning and then night. We do not give her that much of her food, just a spoonful and we mix it up with some veggies (either carrots or green beans). We tend to NEVER use canned veggies, just frozen or fresh, so we can keep it low on the salt intake. We give her treats 2-3 times a day, mainly her Tiny T Bonz or Butler Lean Treats. She sometimes gets the occasional biscuit or greenie. Should we cut back on the treats? Is there something that we should add to her diet that's better for her?
And exercise, we have a fenced in yard so there's no question that we can let her out and she can walk all over wherever she wants, but she has a tendency to just go out there and walk for a few and then want to go inside, or sometimes she'll just walk a few steps and sit down, lol. I hate to get her too worked up because it always seems like she does the choke/gag thing when she gets too hyper. Any suggestions about anything I've asked about/said would be so appreciated.
We're taking her back to have her eye looked at again on Monday morning, so I can ask questions then, I'm just looking for some firsthand experience before I do.