short marathon training

hey!
i recently have been off of running for 3 weeks because of itbs. i’m still not recovered and i’m signed up for the chicago marathon this october. i’ve seen multiple pts who have said i still have time to recover and run, but i wanted to know a coaches perspective too.
before my injury, i was in a great place of maintenance and my longest run was 13.1 miles. i know i would have to start slow and build gradually, but i cant tell if i’ll be ready or if i should pull out.
i will have 12 weeks of training at most, if best case (which i honestly doubt) i run again starting next week. i honestly just feel so frustrated and sad and miss running but know i need to take care of myself- just sucks.

any tips or advice? any training plans that could suit this situation well?