sounds lovely! haha
am i right in thinking that by putting a longer stem in though it would make the seat higher than the handlebars, causing you to lean forward more? As opposed to buying a bigger bike it would all be in proportion and reduce the leaning?
The stem is the part that connects the handlebar to the fork steerer - it won't affect the seat height. I think you mean the seat-post.
A larger bike will normally have a longer head-tube, which does make the height difference between the saddle and bars less, assuming the saddle is in the correct position. The position of the handlebars can also be altered by moving the stem up or down the fork steerer (to some extent) or by fitting a different length or different rise stem.
But - get a bike that fits and then you can tweak the position rather than try to make big changes.