How to edit video properly?

Question

Video processing

I'm trying to deal with the processing of video files, for this I decided to try uploading a video to Instagram, and after downloading, look at the changed parameters and do the same. I did it, but the video that I processed (processed the same original video that I uploaded to Instagram) is worse in quality and the video itself is crooked, not as square as in insta. What am I doing wrong?
Original file

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'parent.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2017-07-03 17:13:07
  Duration: 00:00:12.84, start: 0.000000, bitrate: 42187 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 3840x2160, 41841 kb/s, SAR 1:1 DAR 16:9, 29.36 fps, 29.97 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      rotate          : 90
      creation_time   : 2017-07-03 17:13:07
      handler_name    : VideoHandle
    Side data:
      displaymatrix: rotation of -90.00 degrees

The command with which I convert

ffmpeg -i parent.mp4 -r 30 -b:v 300k -strict -2 -vcodec h264 -vprofile main -b:a 70k -s 640x640 -aspect 1:1 -sar 1:1 odass.mp4

Source converted by me

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'odass.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:00:13.10, start: 0.021333, bitrate: 322 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 640x640 [SAR 1:1 DAR 1:1], 252 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler

Video uploaded from instagram

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'instagram.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:00:12.89, start: 0.042667, bitrate: 307 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 640x640 [SAR 1:1 DAR 1:1], 234 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler