Cycle length change after D&C

I had a 28 day cycle always. Got pregnant, found out nothing was progressing so D&C in July at 9 weeks. Got a period 6 1/2 weeks later, had 3 28 day cycles. Ttc on cycle 4 & now my cycle changed to 25 days. This is my 4th 25 day cycle, has this happen to anyone????? Feel alone in this.....worried Luteal Phase is too short!