OK, well the majority of my 150 or so hours are on 150/152s (I know, boooooooring!
) and I would say that even with the right conditions, 45kts sounds a bit early to rotate for the 152, especially without flap. However, once it gets to 40-45 you've lost the inertia and it's at 55 in the flash of an eye, I generally find. Which sounds like a more sensible speed. Of course, it's all just guidelines really, whether it's a yank or a release to lift off at that speed depends on conditions. I was taught to wait until you feel it wants to. (The 150s I have flown seem to work with Whirly's numbers, but in MPH.)
I instinctively lower the nose slightly to gather momentum as soon a we're well and truly lifted off. This is down to early training and reading 'stick and rudder' from what I can remember, but (obstacle clearance aside) it does go for a more comfortable take off and initial AoC. There has been one occasion when I noticed the weight of the aircraft versus thin air as soon as I lost the ground effect and it's not something I want to repeat!
(Smurph will back me up here.)
Mazzy, just a thought, your physique is probably not best suited to a 152; perhaps since you were dual you were a bit heavy as well as being hot and high? When you look at weight schedules, you realise that a lot of the time it's a choice between fuel or bags!
Most blokes at my club choose to switch to 172s before they complete their training for that reason.