I, too, soooo remember feeling that way when I had my daughter 3 yrs ago. The first 6 weeks were the toughest for me really up until 6 months. My husband was a resident working crazy hours so really I was the one having to hold everything together, and frankly I was falling apart. I remember feeling so tired, worn out, and disconnected. Around 6 weeks, I got a random phone call from my health insurance company saying they were checking in on me. They told me it was a routine post-partum checkup that Blue Cross Blue Shield of Massachusetts did for their clients. Ok, so I was totally honest with answers and they told me I needed counseling.
They recommended a counselor and at that point, I went with no hesitation hoping to find an answer to bring me back to my normal happy self. I went to see the counselor, she asked a zillion questions and she told me I was sleep deprived and didn't want to label me with post-partum depression quite yet until we figured out a way to get the sleep thing corrected. She told me to get a hotel room for a weekend and get away by myself. Really???? No way, I was breastfeeding, I couldn't do that. But what I did do was get a night nanny a couple nights a week which was a life saver for me. My counselor was totally right, I needed sleep. I started working out when my husband was home even if it was for just 30 to 45 minutes at the gym just to have time out for myself. I planned little outings for coffee with friends when I could too.
Post-partum depression isn't usually diagnosed for several months up to I think a yr after delivery. But "post-partum blues" are extremely common secondary to the significant change in your lifestyle, sleep patterns, and the feeling you have no time for yourself.
I totally understand the feeling to keep your little one protected from germs and illness especially this time of year and what you have already been through.
Hang in there is my suggestion. Exercise. If you can afford a night nanny, do it to get some sleep. Try to get out a little, even if its just to see a friend for coffee (bring hand sanitizer for anyone that touches your child if you are worried). As long as your little one is non mobile (not crawling), you can really prevent exposure pretty good with hand sanitizers and not going to a mall or play area where toys are shared. Try to make a deal with your husband about him being the weekend guy to get up with the baby and you the weekday (or try to split it up during the week) - although if you are still breastfeeding this is tough, you may want to pump.
Good luck. It does get better. Don't be afraid to get professional help if you need to, nothing to be ashamed of. Keep the faith. You can do it!
-S.