She might have just fell into the comfortable pattern. In the beginning in the 'honeymoon period' its all exciting and new and text and communication is flying. After a few months things seem to die down a bit. Does not mean she loves you less, it just means that theres literally no need to reaffirm I love you's every 5 mins. If shes engaging with you in person and clearly still showing an interest then I dont think you have to worry too much.
Some people do not feel the need to say I love you all the time. They are content in the fact that words do not need to express that emotion because the love is already there between both people. I went out with someone who said it like all the time. It really got my back up in the end as I did not feel the need to keep reaffirming it over and and over. It came across as too needy. Likewise with texting, expecting a text back in like 5 mins or they dont love you. It can be offputting.
Now im not saying like ghost the girl, but try not to let it bother you too much. She is texting you back, so shes not ghosting you.
Now If her texts are frequent to the point of hardly at all, maybe one word answers when you ask her something, then perhaps shes being a bit off, but then you would need to address it.'' Are you ok? you seemed very short on your texts earlier on, so just wondering if your alright?'' might encourage her to talk as she may have something on her mind. It might be you, it might be work/school or even something else as to why shes distant.