Long story short, I was on a short trip, mostly highway miles. Everything seemed fine until I came to a stop at my exits off ramp. As I took off from the stop sign, I noticed a complete loss of power. I promptly limped my way to the nearest auto parts store where I determined the issue was caused by a transmission line leak which lead the system to go dry. I filled her back up with fluid, and was going to make my way to my destination where I could better inspect/fix the leak. As I go to reverse out of the parking space, I no longer had reverse. Just revved to around 3k, but absolutely no power. I was able to coast backwards enough to put it into drive, but once again very sluggish starting off. No reverse, no 1st, and no 2nd. 3rd and 4th seemed fine as after I got up to around 30, it pulled normally. Tried manually shifting, same deal. I have searched the web extensively, but nothing comes up as far as my full list of symptoms. So far all I have pulled the trans and checked all solenoids which are functional. Before I tear into the case (never attempted before), what component (s) should I be looking at if any in particular? Also, I have read that I can get into the case to remove the clutch packs WITHOUT removing any valve body components, has anyone had any experience doing so before? Thanks in advance guys!
EDIT; Reverse felt as if it wasn't engaging at all, the car felt like it was under load in neutral

 

How much fluid do you add?