My 4 kids are all grown, healthy, and only 1 is a bit overweight. 'Back then' I started juice and cereals PER DOCTORS' RECOMMENDATIONS (which keep changing!!) at 6 WEEKS (not months). One did have some kind of allergic rash for his first year that no one could figure out (family practice dr, pediatritions, dermatologist). Not once did any Dr. tell me to take him off all solids and re-introduce them one at a time for a week each, although I WISH someone HAD. I think it could've been narrowed down to a 'cause').
Anyway, if she's already tolerating cereal and applesauce (which is acidic and would've caused some reaction [diaper rash, breaking out, etc] if she was allergic to it), I'd say it's fine to introduce mashed potatoes, green beans, peas, avacado, carrots, sweet potatoes, etc. Just start each new addition ONE AT A TIME FOR A WEEK (or more) EACH! That way, you can tell if anything bothers her at all. Just continue to give her low-salt/low-sugar items and thin them down w/water or breastmilk/formula if they're too 'paste-y' and thick.
(2 of my daughter's 3 little ones would get a yellow nose when they'd eat carrots, pumpkin, or sweet potatoes! LOL I guess it's the beta carotine, but it's cute).