It's not about if an RJ job is a step 'backwards'. You should be focusing on what gets you to your final job fastest.
To be competitive (average resume) right now you need about 7000+, 4000 PIC, some TPIC, several type ratings, and a four year degree.
1,800 TT, 1600 jet FO, no 121, no PIC, just isn't competitive. Look at the resumes posted by guys getting hired and figure out how to make your future resume mimic theirs.
What's get you there quickest? 787 is going to be more FO time. You'll have to hope that the pilot shortage decreases the value given to PIC time if you stay an FO for the next 5-7 years. If you go to an AA WO you'll be able to flow in 5-7 (?) years. And it looks like you might upgrade in 3(?) years. So you'd upgrade with approx 4,000 TT. Three years later you'd be at approx 6,000 TT and 2,000 121 TPIC.