Need Extra Semester But Accepted Boutique SA Offer

Hi everyone. Apologies in advance if there has already been a discussion regarding a similar topic.

To give a bit of background, I'm a junior who has already signed for a 2022 SA position. With that being said, I just transferred to the school I currently attend and after many tries of appealing credits, my current school has not adjusted my credits. So, now I have to take an extra semester and graduate in December 2023 instead of May 2023.

I'm still appealing the credits, however, if they are not approved would I still be able to obtain a return offer with the boutique I'm working at this Summer and just start later? If not, do you think it's likely to negotiate another summer analyst offer for summer 2023? Not sure how feasible the latter is since I'm sure it would mean that I could be messing with their future full-time/SA recruitment. 

I feel conflicted about being in this position but I do not want to burn any bridges with the firm I will be working at this summer. But yea, right now it's not looking like I'd be able to join their full-time class (assuming I get a return offer) if I graduate in December.