Homebrew PCBs

Hello,
I made another PCB, this time more complex, and tried to solve the
problems I had, especially the photo-resist coming out when tried to
clean the board's surface while developing.
I was not able to solve this...

I'm thinking that may happend because of some light getting trough the
dark areas in the transparency, so expossing a bit, and so making
photo-resist come out when I try to clean the board while developing...
If I take out the board and clean with lots of fresh water, then it
does not come out anymore.

Now the question... I don't know how to solve this. Maybe:

- Less expossure time (the problem is I need 0.3mm track separation
sometimes, so it's tricky, as little time doesn't allow to separate them).
- Use acetate paper and laser printer (I was using inkjet paper,
printing in the rough side with a inkjet printer. Should this be a
problem??)
- Take the board out of the developer sooner. When the image appears,
I usually left the board in for about 1 or 1,5 minutes.

Do you think this could be right?
Any advice?

thank you!