Car Seat help! fitting 3 across

We are having a car seat/ car dilemma and it's stressing me out! I have a 19 month old who is in a rear facing convertible car seat (Graco milestone) it's pretty slim as far as convertible seats go. I drive a 2015 jeep Cherokee, we have tried a few different slim infant seats (Chico key fit, Graco snugride) and can't seem to fit 3 across in my car. I REALLY don't want to have to get a new car, I just bought it this summer and still owe 14k on it... but I don't know if I'll have a choice. 

Has anyone had luck fitting one convertible seat and two infants seats in a mid sized SUV? I'm willing to look at thinner convertible seats, but I hate to buy them and not know if it will work.