How long does it take to get back into shape? I'm getting very discouraged!!?

I am a 21 year old female and I am 5'5" and weigh 126. I used to be in decent shape but I stopped working out regularly for the past couple of years (I would still work out but it was sporadic and very inconsisent, for the most part I went back to my sedentary ways). So I got super sick in December and January (from stress from work and school, getting ecoli, and having an autoimmune disease called lupus that makes it worse) and went down to 115 lbs. I kinda liked it but I also didn't because I felt really weak and frail and wanted to gain it back. So I did, and since the beginning of this month I have been exercising a lot more than I have in recent years, and I have been eating healthy like crazy too. I want to be 120 lbs give or take. But the scale won't budge! I have been weighing myself everyday and it's like no matter what I do...idk. It's just so discouraging. Am I meant too be a porky or something? Also, when I work out I get out of breath easily and have to take a lot of breaks or stop for a few seconds (I mostly run on the treadmill but I have been doing some weights too) I feel that since I have been working out for a month I should be getting results in not just weight loss but better endurance and strength...but I am not making any progress! How long should it take, should it take a few more months to a year? My guy says I should not be hard on myself because of what I went through when I was really sick, especially when I went to the hospital. I am just getting discouraged...and reading those fitness magazines for women are not helping either. I am just trying to do my best to be healthy and fit again but it feels like I m working hard for nothing.