I think the obvious answer here is to continue to rely on your therapist for help, and do not be afraid to seek other therapists if you feel like the sessions are not helpful.

Personally, while I do not suffer from severe “racing thoughts”, I do get interrupted a lot by random thoughts and ideas when reading. I find it helpful to not treat these ideas that negatively. At their presence I try not to judge myself or blame these thoughts. I acknowledge that they appeared in my mind, and carry on rereading parts that I missed. I try to not get anxious when I am interrupted, and tell myself that I can take it at my own pace.

Hopefully that helps and wish you the best of luck!