Closing the distance and not freezing/retreating?

As the title outlines, I need tips and tricks for closing the distance when sparring.

I’m only about a month, maybe two in Muay Thai so I know a lot will come with time but I want some pointers to focus on. Whenever I do sparring with people at the gym, I both struggle with closing the distance and either freezing up or retreating.

One of the coaches said that it comes with time and to focus more on attending the defence classes to build up my skills in that area, but that I have already pretty much perfected how to evade kicks & punches.

My issue is that even though I have been whacked with a few punches to the face & kicks to the leg or ribs, I just can’t get out of my head and get in to close the distance. Everyone has such a tight guard that it makes me freeze up not knowing how to break the guard and get through.

Does anyone have tips on types of drills to help or tips to get out of my head and just go with the flow?

Thank you!!