Upcoming I-751 & N400 Combo interview!! Advice needed!

[Mattgz14 0]

I have been on this forum on and off so I would consider any kind of comment would be helpful and useful for me.
I filed joint i-751 with my ex spouse back in December 2016.Things did not went well and we decided to Divorce and it  happened in May 2018.I let the USCIS know before receiving my divorce decree.We sent an amendment with my lawyer,divorce was finalized in may 2018,USCIS has sent me a RFE in July 2018 asking for my signature to switch the case in to a divorce waiver.But also on RFE it was saying that we don’t shared  commingled finances.They also stated that there was a huge wire(my parents send me money for me to purchase car) transfer on my bank statement,and my 2016 taxes were showing much less income.They asked me where is this money comes from.Me and my lawyer reviewed everything one more time and sent them a much better package in September explaining that transaction.10 days later our response to RFE(I’ll attach it here).My status changed it to We sent your case to your local field office for an interview I honestly know so many people has no evidence but they have been approved with a divorce waiver and without an interview,since then no action on i751.My office is Miami Field Offfice.When I went there for stamp.They told me that my case is there.So since there is no action on my i751 my lawyer advised me to file n400 under 5 year rule.Which I filed in December 2019.They scheduled me and n400 interview for March 2020 but unfortunately as all of you know its been cancelled due to Covid19.They rescheduled my interview for beginning of September.What should I do to get both interviews be done at the same time?cause in the interview letter it says that n400 interview no mentions about i751.My i751 is pending for almost 4 years.It’s been a disaster for me.I have been waiting for this process to finalize to so I can sure that I will be living here the rest of my life and start my new business with peace of mind.I’m having really hard time because of this waiting game.Mentally  is more though for me.My parents are also old.I couldn’t see them for a year.I need you guys advises what steps should I take or can I take to get this interview happened.Do you guys think if there is something wrong with my case since they went rough in that RFE letter.Any kind of comment will be appreciated!!also here is my rfe letter back in 2018.