Export file size is the same regardless of length of video??

This is the order I've done my work...

1. . Received a mp4 video [Let's call it "video original"]  size: 631MB;  2:03:59  length in time
2.   Chopped off intros and outros and added my own png slides  and a bit of music both ends.
   • intro added 3 x png slides, 11 secs total
   • outro  3 x png slides, 13 secs total
   • [video edited 1]
   • size 1.01 GB , length 2:03:00 ( I didn't take much notice of this at the time, that it had almost doubled in size!)
3. Compressed the video using Premiere Pro by dialling down the bitrate
   • size 457 MB, length 2:03:00
   • [video compressed]
4. The membership software I use requires videos less than 200MB, and I didn't want to lose the intro and outro editingI had done the "video original"  so I want to use the "video compressed" version, which I presumed I could chop into 3 parts and get videos around 150MB each. NOT SO!!! This is where the problem starts...
   
5. "Video compressed" is put into Premiere Pro,
   • chopped off two thirds of 'video compressed"
   • chop off the old intro,
   • insert new intro,
   • add new outro,
   • add music at both ends
   • Export tells me that the new video will be 1.6 GB; length 44:4:23
   • WTF????

I realise I could have made some mistakes at step 2 conversion, presets and export, but I'm happy to work with "video compressed" chopped into 3 parts.

6.   I've now gone into Premiere Pro to try all sorts of variations: could it be my png slides? the music?Change to different presets, legnth of video? but this is what happens:- ( now using preset Youtube SD 480 to match source sequence frame size)

A> Export with full length video compressed

Size 1.567 GB length 1:42:51:26

B> Get rid of music and pngs

Size 1.567 Gb , length 1:42:51:26

C> chop video to one-third size
Size 1.567GB  length . time is still 1:42:51:26 What???
There is a yellow time to what I had cut it to marked on image below in red.
Is the export still reading the whole clip???? Even when I cut down the clip to 16secs  the export reads 1.567GB. What is going on??

I cut the clip with the razor blade and "clear:" the portions not needed. Is that not enough?

thanks for your help in advance...

Frustrated..

Linda