TS, I think their opinions are valid. I asked my wife (we met when working at the same company) and she echo-ed similar response with the above ladies.
Just to add on what others have said:
Ask her out again and gauge her response from there. If she reject you again I think the answer is clear: either she is not interested in you or she's not keen in any romantic relationship. Usually, a simple meal together happens between colleagues, if she rejects means she's obviously not giving any chances or even feeling repulsive.
When a girl has some degree of interest in you, they will find ways to accommodate your timing, try to meet up or strike small talk with you. However, in your replies, she appeared to be hard to catch or busy.. it could be that she is actively avoiding you but appearing to be polite. When my wife and I were not dating and were still normal colleagues, I noticed her pushing back her lunch schedule to meet mine. I was in the sales department and she was in accounting and my lunch was very late around 2.00pm. I wasn't aware at that time but her colleagues hinted to me haha.
My wife also shared an interesting point. She said that if a lady has even a slight interest with her male colleague, the lady will try to give an impression of an ideal partner rather than an impression of a workaholic. A good hint is she will actively whatsapp you to chat even if you do not initiate it.
Hope it helps. Good luck and have fun!
