Many schools are going to require your final two years, or 60 credits, at that school, so DePaul is not unusual in that aspect. If you already have 70 credits, you’ll still need to take 60 to graduate, or a certain number of upper division courses at that school, or particular courses. I don’t know that getting another 10-15 credits and then transferring the 70 you have plus another 10 will help you get out of school any faster.
If you don’t want to go to DePaul, don’t go there. I think you are stuck it thinking that because you were at a top 50 school coming out of high school you should only apply to top ranked schools. You have to look at where you are now, not where you were coming out of high school. A 3.2 at college is not a high school 3.2, so you might be a good transfer candidate.