Meth has a higher bioavailability when consumed intranasal (70~80% )as well as smoked (~90% ) With oral (~40-60% ) use, the dose should be higher for the desired effect. The dose info on Erowid, however, states that oral has a slightly lower dose than smoking and snorting, which have about the same, snorting having the lower of the two. I'm confused by that, but can't find a possible explaination on that part other than they're based on different sources of which one was wrong.
That doesn't give an explaination for your personal account though. You should've either experienced about the same effect (erowid.org) or you should've felt less, when taking it orally.(taimapedia.org) My theory is that you're either doing something wrong or there is some physical cause. If you're snorting this could be inhaling too deeply (wrong) or a damaged/clogged mucous membrane. In case you're smoking, you could be inhaling too softly (ironic, isn't it) or you could have some form if lung issue. I personally snort most drugs, so I'm sorry for not being able to go into more detail considering the lung issue. Usually I'd google what could be a cause, but I've spent way too long searching for the bioavailability/dose inconsistency problem and just can't be bothered.
Likely solutions:
Insufflated - Don't snort it into your throat and get a nasal congestant, preferably a simple saline solution, since stronger products dry out the nose over time, making matters worse. Make sure to not use the congestant prior to snorting, as the diffusion would be hindered due to the lowered osmotic pressure. Final method I can think of that might increase the absorption would be to hydrate your body well, if you're not doing so yet.* Take into account
Smoking - Inhale the smoke
deeply and just hold it in for some time, so it can fully absorb.** As for a possible lung problem, the only advice I can give is to go see a doctor and have him check your lungs.***
Elaborations:
*The transport within the body goes through your bloodstream and lymphatic system, which both require to be hydrated sufficiently. The lymphatic system is responsible for the disposal of excess materials. Without enough hydration, your lymph glands could get clogged, causing inflamations and distortions of the transport flow.
**Meth in it's base form, which the vapor is, is only slightly soluble in water and can therefore not pass the membrane as easily as some other substances. It's important with absorption through the lung alveoli for a substance to be water soluble, because it enters the bloodstream, which is aqueous, instantly after passing the membrane.
***Methamphetamine base's structure allows it to be easily pass through the mucus and membrane, into the bloodstream. However, the absorption through the membrane is based on solubility in water (polar), which is less than its solubility in the mucus (apolar.) Taking that into account, insufficient mucus secretion would cause the absorption to be inhibited, but not prevented, so once again: Hydrate sufficiently.
Hydration came up twice so that rings some alarms. Methamphetamine use causes dehydration and the average human is already not drinking enough, so this is something to seriously consider as cause and is also harmful to your wellbeing. Drinking a gallon of water is dangerous as well! Don't drink too much at once and make sure your nutrition consists of enough glucose and salt. Drinking too much water without salt causes the brain to be unable to restore the chemical imbalance. If you don't consume enough glucose, the water isn't absobed properly.
Lastly
I just came up with the fact that your meth might be cut with either an active substance with similar effects, but different bioavailability
or an active substance that inhibits the effects of meth, but doesn't function or functions less when taken orally.
PS:
I also asked a friend with more knowledge on the subject and he thought it was because you're a pancake.
No seriously, those were his words, not mine. He didn't take it seriously
