I'm really sorry @AMFM I can't remember when he did specific things like eye contact etc. DD2 had an accident and burnt herself (she is completely fine now) when DS was 4.5 mths old and at the redressing appointments our GP would always ask how DS was going. That is the only thing that fixes the timeline for me during that period.
Sorry I can't be more help I'm shocking for remembering stuff like that at the best of times but with kinder run, doctors appointments and just general busyness it all just blends into one.
Take heart from the fact you have already noticed an improvement and he loves his kisses and cuddles.
Maybe you could take a video of him every couple of days or so and then when you look back through them you can see how much improvement he has made. That was one thing I wished we had done after we got the all clear.